How many zeroes are there at the end of the number N, if N = 60! + 120! ?  Choose one
A) 12 B) 14 C) 16 D) 18 E) 20

Rationale: the number of zeroes at the end of 60 ! will be less than the number of zeroes at the end of 120 ! hence it is sufficient to calculate the number of zeroes at the end of 60 ! the number of zeroes = [ 60 / 5 ] + [ 60 / 25 ] + [ 60 / 125 ] = 12 + 2 + 0 = 14 the answer is b .
Answer: B