BRAIN TEASERS THREAD

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[ QUOTE ]
One of my favorites from long ago, I hope I get it right. I have purposefully changed the usual wording to prevent easy googling:

A & B are integers greater than 1 and less than 100.

Mr. Add knows (A+B)
Mr. Multiply knows (A*B)

Mr. Add says to Mr. Multiply, "You don't know A and B."
Mr. Multiply says, "Now I do know A and B."
Mr. Add says, "Now I do too."

What are A & B?

~MagicMan

[/ QUOTE ] A*B can't be prime, or else mr. multiply would know. thats where my ideas stopped. i also suspect that A*B must be less than 1600, as 1600 might be the largest number represented by two products of numbers between 1-100 (16*100 and 40*40).