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bhaskar438
Harley1980
When integer A divided by 9 remainder is X, when integer B divided by 9 the remainder is Y. What is \(|X-Y|\)?

1) When \(A + B\) divided by 9 remainder is 6
2) When \(A * B\) divided by 9 remainder is 8

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I believe the correct answer to this question is E.
Since X and Y are remainders when divided by 9, they must each be less than 9. X<9 and Y<9, therefore X+Y<18 and X*Y<81.
X+Y = 9k + 6 and X*Y= 9z + 8. The only values that X+Y can take in this problem are 6 and 15. The only values that X*Y can take in this problem are 8,17,26,35,44,53,62,71, and 80. There is no such solution for sum equal 6 that satisfies X+Y = 9k + 6 and X*Y= 9z + 8. For sum equal to 15 there are 4 solutions that satisfy both X+Y = 9k + 6 and X*Y= 9z + 8, which are (2,13), (13,2), (4,11) and (11,4). The absolute difference can be either 11 or 7.

Hello bhaskar438

There is no such solution for sum equal 6 that satisfies X+Y = 9k + 6 and X*Y= 9z + 8.

A = 11 and B = 13
X = 2 and Y =4
X + Y = 6
X * Y = 8

I think you miss the possibility that k and z can be equal to 0

For sum equal to 15 there are 4 solutions that satisfy both X+Y = 9k + 6 and X*Y= 9z + 8, which are (2,13), (13,2), (4,11) and (11,4).
X and Y can not be more than 9 so these solutions are out
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Harley1980
bhaskar438
Harley1980
When integer A divided by 9 remainder is X, when integer B divided by 9 the remainder is Y. What is \(|X-Y|\)?

1) When \(A + B\) divided by 9 remainder is 6
2) When \(A * B\) divided by 9 remainder is 8

Source: self-made
I believe the correct answer to this question is E.
Since X and Y are remainders when divided by 9, they must each be less than 9. X<9 and Y<9, therefore X+Y<18 and X*Y<81.
X+Y = 9k + 6 and X*Y= 9z + 8. The only values that X+Y can take in this problem are 6 and 15. The only values that X*Y can take in this problem are 8,17,26,35,44,53,62,71, and 80. There is no such solution for sum equal 6 that satisfies X+Y = 9k + 6 and X*Y= 9z + 8. For sum equal to 15 there are 4 solutions that satisfy both X+Y = 9k + 6 and X*Y= 9z + 8, which are (2,13), (13,2), (4,11) and (11,4). The absolute difference can be either 11 or 7.

Hello bhaskar438

There is no such solution for sum equal 6 that satisfies X+Y = 9k + 6 and X*Y= 9z + 8.

A = 11 and B = 13
X = 2 and Y =4
X + Y = 6
X * Y = 8

I think you miss the possibility that k and z can be equal to 0

For sum equal to 15 there are 4 solutions that satisfy both X+Y = 9k + 6 and X*Y= 9z + 8, which are (2,13), (13,2), (4,11) and (11,4).
X and Y can not be more than 9 so these solutions are out

Thank you. I just realized even though I mentioned earlier that X<9 and Y<9, I forgot to reject the solutions afterward. There are no valid solutions for sum equal to 15. For sum equal 6 case, I accidentally took (2,3) instead of (2,4) and missed the solution because 6 is not 8 more than a multiple of 9.
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