Finding the values $A$ can take. [closed]
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$$A2B2 equiv 0 space space (textmod space 12)$$
$$A-B>4$$
Find the values $A$ can take.
Could you help me out?
Regards
modular-arithmetic divisibility
closed as off-topic by JavaMan, Shailesh, Brahadeesh, gammatester, amWhy Aug 6 at 13:35
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question is missing context or other details: Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – JavaMan, Shailesh, Brahadeesh, amWhy
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up vote
-3
down vote
favorite
$$A2B2 equiv 0 space space (textmod space 12)$$
$$A-B>4$$
Find the values $A$ can take.
Could you help me out?
Regards
modular-arithmetic divisibility
closed as off-topic by JavaMan, Shailesh, Brahadeesh, gammatester, amWhy Aug 6 at 13:35
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question is missing context or other details: Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – JavaMan, Shailesh, Brahadeesh, amWhy
1
Should that be $A^2B^2$? What are your thoughts on the problem? What you have tried? Where are you stuck?
– JavaMan
Aug 6 at 13:00
What have you tried so far? Where do you get stuck? What does it mean $A2B2$?
– Taroccoesbrocco
Aug 6 at 13:01
@JavaMan That shouldn't. I'm beginner at modular arithmetics. Hence I couldn't show my attempt.
– Hamilton
Aug 6 at 13:01
So then what is $A2B2$?
– JavaMan
Aug 6 at 13:02
@JavaMan $A2B2$ is a number
– Hamilton
Aug 6 at 13:03
 |Â
show 1 more comment
up vote
-3
down vote
favorite
up vote
-3
down vote
favorite
$$A2B2 equiv 0 space space (textmod space 12)$$
$$A-B>4$$
Find the values $A$ can take.
Could you help me out?
Regards
modular-arithmetic divisibility
$$A2B2 equiv 0 space space (textmod space 12)$$
$$A-B>4$$
Find the values $A$ can take.
Could you help me out?
Regards
modular-arithmetic divisibility
asked Aug 6 at 12:59


Hamilton
967
967
closed as off-topic by JavaMan, Shailesh, Brahadeesh, gammatester, amWhy Aug 6 at 13:35
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question is missing context or other details: Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – JavaMan, Shailesh, Brahadeesh, amWhy
closed as off-topic by JavaMan, Shailesh, Brahadeesh, gammatester, amWhy Aug 6 at 13:35
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question is missing context or other details: Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – JavaMan, Shailesh, Brahadeesh, amWhy
1
Should that be $A^2B^2$? What are your thoughts on the problem? What you have tried? Where are you stuck?
– JavaMan
Aug 6 at 13:00
What have you tried so far? Where do you get stuck? What does it mean $A2B2$?
– Taroccoesbrocco
Aug 6 at 13:01
@JavaMan That shouldn't. I'm beginner at modular arithmetics. Hence I couldn't show my attempt.
– Hamilton
Aug 6 at 13:01
So then what is $A2B2$?
– JavaMan
Aug 6 at 13:02
@JavaMan $A2B2$ is a number
– Hamilton
Aug 6 at 13:03
 |Â
show 1 more comment
1
Should that be $A^2B^2$? What are your thoughts on the problem? What you have tried? Where are you stuck?
– JavaMan
Aug 6 at 13:00
What have you tried so far? Where do you get stuck? What does it mean $A2B2$?
– Taroccoesbrocco
Aug 6 at 13:01
@JavaMan That shouldn't. I'm beginner at modular arithmetics. Hence I couldn't show my attempt.
– Hamilton
Aug 6 at 13:01
So then what is $A2B2$?
– JavaMan
Aug 6 at 13:02
@JavaMan $A2B2$ is a number
– Hamilton
Aug 6 at 13:03
1
1
Should that be $A^2B^2$? What are your thoughts on the problem? What you have tried? Where are you stuck?
– JavaMan
Aug 6 at 13:00
Should that be $A^2B^2$? What are your thoughts on the problem? What you have tried? Where are you stuck?
– JavaMan
Aug 6 at 13:00
What have you tried so far? Where do you get stuck? What does it mean $A2B2$?
– Taroccoesbrocco
Aug 6 at 13:01
What have you tried so far? Where do you get stuck? What does it mean $A2B2$?
– Taroccoesbrocco
Aug 6 at 13:01
@JavaMan That shouldn't. I'm beginner at modular arithmetics. Hence I couldn't show my attempt.
– Hamilton
Aug 6 at 13:01
@JavaMan That shouldn't. I'm beginner at modular arithmetics. Hence I couldn't show my attempt.
– Hamilton
Aug 6 at 13:01
So then what is $A2B2$?
– JavaMan
Aug 6 at 13:02
So then what is $A2B2$?
– JavaMan
Aug 6 at 13:02
@JavaMan $A2B2$ is a number
– Hamilton
Aug 6 at 13:03
@JavaMan $A2B2$ is a number
– Hamilton
Aug 6 at 13:03
 |Â
show 1 more comment
2 Answers
2
active
oldest
votes
up vote
0
down vote
accepted
Note that my answer is based off the comment the OP said: "$A2B2$ is a number". If this is not what they are looking for, then I will edit my answer later.
What we want is a four digit number $A2B2$ that satisfies the conditions given above.
Condition 1: $A2B2 equiv 0 mod12$
This means that our number must be divisible by $12 = 4 times 3$. For a four digit number to be divisible by $4$, then the last two digits must either be a multiple of $4$ or both be zero. For one to be divisible by $3$, we need each digit added up to be divisible by $3$ (if you didn't know of this trick, it can be proved if you have some understanding of proofs and divisibility). A number that is divisible by both $4$ and $3$ will be divisible by $12$ as well.
Condition 2: $A-B gt 4$ this is a straightforward thing to check after we check for condition 1.
Using condition 1, we can find all possible values for $B$:
- $A202 notequiv 0 mod 4 Rightarrow B neq 0$
- $A212 equiv 0 mod 4 Rightarrow B = 1$
- $A222 notequiv 0 mod 4 Rightarrow B neq 2$
- $A232 equiv 0 mod 4 Rightarrow B=3$
- $A242 notequiv 0 mod 4 Rightarrow B neq 4$
- $A252 equiv 0 mod 4 Rightarrow B=5$
- $A262 notequiv 0 mod 4 Rightarrow B neq 6$
- $A272 equiv 0 mod 4 Rightarrow B = 7$
- $A282 notequiv 0 mod 4 Rightarrow B neq 8$
- $A292 equiv 0 mod 4 Rightarrow B=9$
So $B$ could be either $1,3,5,7,9$, but take note that if $B$ were to be equal to $5,7, or 9$, then $A$ would need to be larger than $9$ by condition 2 which wouldn't make sense using the assumption that $A2B2$ is a four digit number. Therefore we now know for sure that $B = 1$ or $B=3$ and our number is either of the form: $$A212$$
Or $$A232$$
Now using condition 2, we can deduce that $A$ can be any of the following: $6,7,8,9$. Remember that our number must be divisible by three, so we need $A + 2 + 1 + 2$ to be a multiple of $3$, and this can only happen when $A = 7$.
If we let $B=3$ then we need $A+2+3+2$ to be a multiple of three and $A=8$ works.
So our only allowed value for $A$ is $7$ if $B=1$ or $8$ if $B=3$, and we can check with a calculator that $$7212 ÷ 12 = 601$$
$$7-1 gt 4$$
Or $$8232÷12 = 686$$
$$8-3 gt 4$$
If in fact you did mean to say $A^2B^2$ then see that we only need one of the perfect squares to be divisible by $12$. The smallest perfect square that $12$ divides into is $36 = 6^2$. If we let $A$ be $6$ then we simply set $B$ to be either $0$ or $pm1$. Otherwise set $B=6$ and let $A ge 11$.
So either $|A|=6$ or $|A| ge 11$
add a comment |Â
up vote
0
down vote
If I were you, and admitting $$A2B2$$ is $$A^2B^2$$, I would take a look at the different values that a square number can take modulo 12.
add a comment |Â
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
0
down vote
accepted
Note that my answer is based off the comment the OP said: "$A2B2$ is a number". If this is not what they are looking for, then I will edit my answer later.
What we want is a four digit number $A2B2$ that satisfies the conditions given above.
Condition 1: $A2B2 equiv 0 mod12$
This means that our number must be divisible by $12 = 4 times 3$. For a four digit number to be divisible by $4$, then the last two digits must either be a multiple of $4$ or both be zero. For one to be divisible by $3$, we need each digit added up to be divisible by $3$ (if you didn't know of this trick, it can be proved if you have some understanding of proofs and divisibility). A number that is divisible by both $4$ and $3$ will be divisible by $12$ as well.
Condition 2: $A-B gt 4$ this is a straightforward thing to check after we check for condition 1.
Using condition 1, we can find all possible values for $B$:
- $A202 notequiv 0 mod 4 Rightarrow B neq 0$
- $A212 equiv 0 mod 4 Rightarrow B = 1$
- $A222 notequiv 0 mod 4 Rightarrow B neq 2$
- $A232 equiv 0 mod 4 Rightarrow B=3$
- $A242 notequiv 0 mod 4 Rightarrow B neq 4$
- $A252 equiv 0 mod 4 Rightarrow B=5$
- $A262 notequiv 0 mod 4 Rightarrow B neq 6$
- $A272 equiv 0 mod 4 Rightarrow B = 7$
- $A282 notequiv 0 mod 4 Rightarrow B neq 8$
- $A292 equiv 0 mod 4 Rightarrow B=9$
So $B$ could be either $1,3,5,7,9$, but take note that if $B$ were to be equal to $5,7, or 9$, then $A$ would need to be larger than $9$ by condition 2 which wouldn't make sense using the assumption that $A2B2$ is a four digit number. Therefore we now know for sure that $B = 1$ or $B=3$ and our number is either of the form: $$A212$$
Or $$A232$$
Now using condition 2, we can deduce that $A$ can be any of the following: $6,7,8,9$. Remember that our number must be divisible by three, so we need $A + 2 + 1 + 2$ to be a multiple of $3$, and this can only happen when $A = 7$.
If we let $B=3$ then we need $A+2+3+2$ to be a multiple of three and $A=8$ works.
So our only allowed value for $A$ is $7$ if $B=1$ or $8$ if $B=3$, and we can check with a calculator that $$7212 ÷ 12 = 601$$
$$7-1 gt 4$$
Or $$8232÷12 = 686$$
$$8-3 gt 4$$
If in fact you did mean to say $A^2B^2$ then see that we only need one of the perfect squares to be divisible by $12$. The smallest perfect square that $12$ divides into is $36 = 6^2$. If we let $A$ be $6$ then we simply set $B$ to be either $0$ or $pm1$. Otherwise set $B=6$ and let $A ge 11$.
So either $|A|=6$ or $|A| ge 11$
add a comment |Â
up vote
0
down vote
accepted
Note that my answer is based off the comment the OP said: "$A2B2$ is a number". If this is not what they are looking for, then I will edit my answer later.
What we want is a four digit number $A2B2$ that satisfies the conditions given above.
Condition 1: $A2B2 equiv 0 mod12$
This means that our number must be divisible by $12 = 4 times 3$. For a four digit number to be divisible by $4$, then the last two digits must either be a multiple of $4$ or both be zero. For one to be divisible by $3$, we need each digit added up to be divisible by $3$ (if you didn't know of this trick, it can be proved if you have some understanding of proofs and divisibility). A number that is divisible by both $4$ and $3$ will be divisible by $12$ as well.
Condition 2: $A-B gt 4$ this is a straightforward thing to check after we check for condition 1.
Using condition 1, we can find all possible values for $B$:
- $A202 notequiv 0 mod 4 Rightarrow B neq 0$
- $A212 equiv 0 mod 4 Rightarrow B = 1$
- $A222 notequiv 0 mod 4 Rightarrow B neq 2$
- $A232 equiv 0 mod 4 Rightarrow B=3$
- $A242 notequiv 0 mod 4 Rightarrow B neq 4$
- $A252 equiv 0 mod 4 Rightarrow B=5$
- $A262 notequiv 0 mod 4 Rightarrow B neq 6$
- $A272 equiv 0 mod 4 Rightarrow B = 7$
- $A282 notequiv 0 mod 4 Rightarrow B neq 8$
- $A292 equiv 0 mod 4 Rightarrow B=9$
So $B$ could be either $1,3,5,7,9$, but take note that if $B$ were to be equal to $5,7, or 9$, then $A$ would need to be larger than $9$ by condition 2 which wouldn't make sense using the assumption that $A2B2$ is a four digit number. Therefore we now know for sure that $B = 1$ or $B=3$ and our number is either of the form: $$A212$$
Or $$A232$$
Now using condition 2, we can deduce that $A$ can be any of the following: $6,7,8,9$. Remember that our number must be divisible by three, so we need $A + 2 + 1 + 2$ to be a multiple of $3$, and this can only happen when $A = 7$.
If we let $B=3$ then we need $A+2+3+2$ to be a multiple of three and $A=8$ works.
So our only allowed value for $A$ is $7$ if $B=1$ or $8$ if $B=3$, and we can check with a calculator that $$7212 ÷ 12 = 601$$
$$7-1 gt 4$$
Or $$8232÷12 = 686$$
$$8-3 gt 4$$
If in fact you did mean to say $A^2B^2$ then see that we only need one of the perfect squares to be divisible by $12$. The smallest perfect square that $12$ divides into is $36 = 6^2$. If we let $A$ be $6$ then we simply set $B$ to be either $0$ or $pm1$. Otherwise set $B=6$ and let $A ge 11$.
So either $|A|=6$ or $|A| ge 11$
add a comment |Â
up vote
0
down vote
accepted
up vote
0
down vote
accepted
Note that my answer is based off the comment the OP said: "$A2B2$ is a number". If this is not what they are looking for, then I will edit my answer later.
What we want is a four digit number $A2B2$ that satisfies the conditions given above.
Condition 1: $A2B2 equiv 0 mod12$
This means that our number must be divisible by $12 = 4 times 3$. For a four digit number to be divisible by $4$, then the last two digits must either be a multiple of $4$ or both be zero. For one to be divisible by $3$, we need each digit added up to be divisible by $3$ (if you didn't know of this trick, it can be proved if you have some understanding of proofs and divisibility). A number that is divisible by both $4$ and $3$ will be divisible by $12$ as well.
Condition 2: $A-B gt 4$ this is a straightforward thing to check after we check for condition 1.
Using condition 1, we can find all possible values for $B$:
- $A202 notequiv 0 mod 4 Rightarrow B neq 0$
- $A212 equiv 0 mod 4 Rightarrow B = 1$
- $A222 notequiv 0 mod 4 Rightarrow B neq 2$
- $A232 equiv 0 mod 4 Rightarrow B=3$
- $A242 notequiv 0 mod 4 Rightarrow B neq 4$
- $A252 equiv 0 mod 4 Rightarrow B=5$
- $A262 notequiv 0 mod 4 Rightarrow B neq 6$
- $A272 equiv 0 mod 4 Rightarrow B = 7$
- $A282 notequiv 0 mod 4 Rightarrow B neq 8$
- $A292 equiv 0 mod 4 Rightarrow B=9$
So $B$ could be either $1,3,5,7,9$, but take note that if $B$ were to be equal to $5,7, or 9$, then $A$ would need to be larger than $9$ by condition 2 which wouldn't make sense using the assumption that $A2B2$ is a four digit number. Therefore we now know for sure that $B = 1$ or $B=3$ and our number is either of the form: $$A212$$
Or $$A232$$
Now using condition 2, we can deduce that $A$ can be any of the following: $6,7,8,9$. Remember that our number must be divisible by three, so we need $A + 2 + 1 + 2$ to be a multiple of $3$, and this can only happen when $A = 7$.
If we let $B=3$ then we need $A+2+3+2$ to be a multiple of three and $A=8$ works.
So our only allowed value for $A$ is $7$ if $B=1$ or $8$ if $B=3$, and we can check with a calculator that $$7212 ÷ 12 = 601$$
$$7-1 gt 4$$
Or $$8232÷12 = 686$$
$$8-3 gt 4$$
If in fact you did mean to say $A^2B^2$ then see that we only need one of the perfect squares to be divisible by $12$. The smallest perfect square that $12$ divides into is $36 = 6^2$. If we let $A$ be $6$ then we simply set $B$ to be either $0$ or $pm1$. Otherwise set $B=6$ and let $A ge 11$.
So either $|A|=6$ or $|A| ge 11$
Note that my answer is based off the comment the OP said: "$A2B2$ is a number". If this is not what they are looking for, then I will edit my answer later.
What we want is a four digit number $A2B2$ that satisfies the conditions given above.
Condition 1: $A2B2 equiv 0 mod12$
This means that our number must be divisible by $12 = 4 times 3$. For a four digit number to be divisible by $4$, then the last two digits must either be a multiple of $4$ or both be zero. For one to be divisible by $3$, we need each digit added up to be divisible by $3$ (if you didn't know of this trick, it can be proved if you have some understanding of proofs and divisibility). A number that is divisible by both $4$ and $3$ will be divisible by $12$ as well.
Condition 2: $A-B gt 4$ this is a straightforward thing to check after we check for condition 1.
Using condition 1, we can find all possible values for $B$:
- $A202 notequiv 0 mod 4 Rightarrow B neq 0$
- $A212 equiv 0 mod 4 Rightarrow B = 1$
- $A222 notequiv 0 mod 4 Rightarrow B neq 2$
- $A232 equiv 0 mod 4 Rightarrow B=3$
- $A242 notequiv 0 mod 4 Rightarrow B neq 4$
- $A252 equiv 0 mod 4 Rightarrow B=5$
- $A262 notequiv 0 mod 4 Rightarrow B neq 6$
- $A272 equiv 0 mod 4 Rightarrow B = 7$
- $A282 notequiv 0 mod 4 Rightarrow B neq 8$
- $A292 equiv 0 mod 4 Rightarrow B=9$
So $B$ could be either $1,3,5,7,9$, but take note that if $B$ were to be equal to $5,7, or 9$, then $A$ would need to be larger than $9$ by condition 2 which wouldn't make sense using the assumption that $A2B2$ is a four digit number. Therefore we now know for sure that $B = 1$ or $B=3$ and our number is either of the form: $$A212$$
Or $$A232$$
Now using condition 2, we can deduce that $A$ can be any of the following: $6,7,8,9$. Remember that our number must be divisible by three, so we need $A + 2 + 1 + 2$ to be a multiple of $3$, and this can only happen when $A = 7$.
If we let $B=3$ then we need $A+2+3+2$ to be a multiple of three and $A=8$ works.
So our only allowed value for $A$ is $7$ if $B=1$ or $8$ if $B=3$, and we can check with a calculator that $$7212 ÷ 12 = 601$$
$$7-1 gt 4$$
Or $$8232÷12 = 686$$
$$8-3 gt 4$$
If in fact you did mean to say $A^2B^2$ then see that we only need one of the perfect squares to be divisible by $12$. The smallest perfect square that $12$ divides into is $36 = 6^2$. If we let $A$ be $6$ then we simply set $B$ to be either $0$ or $pm1$. Otherwise set $B=6$ and let $A ge 11$.
So either $|A|=6$ or $|A| ge 11$
edited Aug 6 at 14:08
answered Aug 6 at 13:54


WaveX
1,8211616
1,8211616
add a comment |Â
add a comment |Â
up vote
0
down vote
If I were you, and admitting $$A2B2$$ is $$A^2B^2$$, I would take a look at the different values that a square number can take modulo 12.
add a comment |Â
up vote
0
down vote
If I were you, and admitting $$A2B2$$ is $$A^2B^2$$, I would take a look at the different values that a square number can take modulo 12.
add a comment |Â
up vote
0
down vote
up vote
0
down vote
If I were you, and admitting $$A2B2$$ is $$A^2B^2$$, I would take a look at the different values that a square number can take modulo 12.
If I were you, and admitting $$A2B2$$ is $$A^2B^2$$, I would take a look at the different values that a square number can take modulo 12.
answered Aug 6 at 13:21
Pjonin
3206
3206
add a comment |Â
add a comment |Â
1
Should that be $A^2B^2$? What are your thoughts on the problem? What you have tried? Where are you stuck?
– JavaMan
Aug 6 at 13:00
What have you tried so far? Where do you get stuck? What does it mean $A2B2$?
– Taroccoesbrocco
Aug 6 at 13:01
@JavaMan That shouldn't. I'm beginner at modular arithmetics. Hence I couldn't show my attempt.
– Hamilton
Aug 6 at 13:01
So then what is $A2B2$?
– JavaMan
Aug 6 at 13:02
@JavaMan $A2B2$ is a number
– Hamilton
Aug 6 at 13:03