SherpaPrep wrote:
10! means 10x9x8x7x6x5x4x3x2x1. Just getting that out of the way. So if we want to know the maximum value of x, we basically need to count up how many 3s there are in 10!. Every third integer is divisible by 3, so that's 3, 6, and 9. It's a trap to think you're done here. We should also realize that every ninth integer is divisible by 9, and 9 has two 3s as factors. In other words, 9 should count twice. So x = 4, not 3.
Using similar logic, we know that 5 and 10 have factors of 5, so y must be 2. Thus, 2y = 4 and the answer is C.
Are u really sure ANS is C, I don't see "2y", where is it from?