How many zeroes are there at the end of the following product

How many zeroes are there at the end of the following product?

1 x 5 x 10 x 15 x 20 x 25 x 30 X 35 x 40 x 45 x 50 x 55 x 60

  1. 10
  2. 12
  3. 14
  4. 15

Answer: A

Explanation

Zeros at the end means multiple of 10, i.e. (2 × 5).

So, the number of 2s or the number of 5s (whichever is lesser) will decide the number of zeros at the end of the expression.

Now, 1 × 5 × 10 × 15 × 20 × 25 × 30 × 35 × 40 × 45 × 50 × 55 × 60

= 1 × 5 × (5 × 2) × (5 × 3) × (5 × 22 ) × (5 × 5) × (5 × 3 × 2) × (5 × 7) × (5 × 23 ) × (5 × 9) × (5 × 5 × 2) × (5 × 11) × (5 × 22 × 3)

Here, number of 2s = 10

So, number of 5s = 14

The lesser of the two will determine the number of zeros.

Hence, there will be 10 zeros at the end in the given expression.

  • Exam Year: 2020