Question

If a number ends with $n$ zeroes, what is the number of trailing zeroes in the square of the number?

• A. 3
• B. 4
• C. 5
• D. 6

Answer 1

The correct option is C

5

A number having n zeroes is of the form $a\times {10}^n$
Square of the number is $a^2\times ({10}^n{)}^2=a^2\times {10}^{2n}$
Hence, if a number ends with 'n' zeroes, its square ends with '2n' zeroes.