Let P = 5^5 \times 15^{15} \times 25^{25} \times 35^{35} and Q = 10^{10} \times 20^{20} \times 30^{30} \times 40^{40}. What is the number of consecutive zeros at the end of the sum (P + Q) ?

  1. A. 100
  2. B. 65
  3. C. 50
  4. D. Zero

Correct Answer: D. Zero

Explanation

P is a product of odd multiples of 5, thus it has no factor of 2 and ends in the digit 5. Q is a multiple of 10 and ends in 0. The sum P+Q ends in 5+0=5, hence there are zero consecutive zeros at the end.

Related questions on Arithmetic

Practice more CDS Elementary Mathematics questions