Since 1099 = (2*5)99 = 299599, Every factor of of 1099 is of the form 2p5q p and q can each be 0,1,2,...,99 which is 100 choices each. So there are 100x100 = 10000 factors of 1099 That's the denominator of the desired probability. ---- Next we calculate the numerator of the probability. They are the positive integers of the form 2p5q which are multiples of 1088. So p and q can can each be chosen as 88,89,90,...,99 There are 99 integers from 1 through 99, from which we must subtract the 87 integers from 1 through 87, so there are 99-87 = 12 choices for each of p and q. So there are 12x12 = 144 factors of 1099 which are multiples of 1088. Therefore the desired porobability is. Edwin