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July 30, 2015

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Posted by **Paul** on Tuesday, March 2, 2010 at 8:42pm.

- Math riddle -
**Ms. Sue**, Tuesday, March 2, 2010 at 8:55pmMultiples of 7:

49, 56, 63, 70, 77, 84, 91, 98

Multiples of 8:

48, 56, 64, 72, 80, 88, 96

Which of those numbers answer your question?

- Math riddle -
**MathMate**, Tuesday, March 2, 2010 at 8:55pmAt first sight, the answer is the LCM (Lowest common multiple) of 7 and 8?

Looking further, there is a problem with the question ("but not any other set of single digit number"). Any number divisible by 8 is also divisible by 2 and 4, hence the two-digit number divisible by 7 and 8 will always be divisible by 7, 8, 4 and 2.

- Math riddle -
**Paul**, Tuesday, March 2, 2010 at 8:59pmThanks, Ms. Sue

Mathmate thanks thats what I thought just wanted to make sure maybe it was a misprint on the riddle.

- Math riddle -
**Ms. Sue**, Tuesday, March 2, 2010 at 9:02pmI read the problem as the PAIR of numbers that can go into the two digit numbers. The numbers 7 and 8 are the only single digit PAIR of numbers that fit that description.

- Math riddle -
**MathMate**, Tuesday, March 2, 2010 at 10:35pmMs Sue, I think your interpretation is very reasonable.

However, mathematically speaking, there is no limit on the number of members in a set. As Paul indicated, there is probably a misprint, where it read "but not any other SET of single digit numbers" it is probably supposed to read "but not any other PAIR of single digit numbers".

- Math riddle -
**Ms. Sue**, Tuesday, March 2, 2010 at 10:43pmThanks, MathMate.