Q: If s and t are +ve intergers such that s/t=64.12.Which of the following could be the remainder when s is divided by t?
A) 2
B) 4
C) 8
D) 20
E) 45
Q: The product of all the Prime numbers less than 20 is closest to which of the following powers of 10?
ANS: 10^7.
My point is that is there any other way to solve this kind of questions rather then calculating the product value first.In case some big number ( like (product of all the Prime numbers less than 100) is there then how to solve the question?
A) 2
B) 4
C) 8
D) 20
E) 45
Q: The product of all the Prime numbers less than 20 is closest to which of the following powers of 10?
ANS: 10^7.
My point is that is there any other way to solve this kind of questions rather then calculating the product value first.In case some big number ( like (product of all the Prime numbers less than 100) is there then how to solve the question?

















