Practice30 Create account

The number 700 is squared and written out in full. How many zeros does $70 0^{2}$ end in?

Class 8Squares and Square RootsSquares and Roots

A2
B3
C4
D6

Step-by-Step Solution

700 =

7 \times 100

, so

70 0^{2} = 49 \times 10000 = 490000

, which ends in 4 zeros. Squaring DOUBLES the number of trailing zeros (2 → 4). Answering 2 keeps the original count unchanged and 6 counts zeros that are not there. The answer 3 is impossible for any square: a perfect square always ends in an EVEN number of zeros.

Answer: C) 4

Key idea: Properties of perfect squares

Useful patterns to spot a perfect square (and reject non-squares):

- **Last digit**: a perfect square ends in 0, 1, 4, 5, 6, or 9 — NEVER in 2, 3, 7, or 8. So 142 cannot be a perfect square (ends in 2).
- **Number of zeros at the end**: must be even. 100 is a perfect square

(1 0^{2})

; 1000 is not.
- **Squares of even numbers are even; squares of odd numbers are odd.**
- **Sum of consecutive odd numbers**: 1 + 3 + 5 + … +

(2 n - 1) = n^{2}

. Try it:

1 + 3 + 5 = 9 = 3^{2}

.

These let you reject many candidates without doing any heavy work.

Master this chapter in 30 minutes a day.

Don't just memorise the answer — build a daily practice habit.

Practice 5 Similar Questions Free →

All Squares and Square Roots practice questions

More Class 8 Squares and Square Roots practice

Rahul writes four numbers on the board: 900, 6250, 4900 and 160000. Using only the rule…Find the value of 1 + 3 + 5 + … + 27, that is, all the odd numbers from 1 up to 27.A student keeps subtracting consecutive odd numbers from 121: 121 − 1 = 120, then 120 −…You already know that 60² = 3600. Using the pattern (n + 1)² = n² + 2n + 1, write down…A Pythagorean triplet is built using the form 2m, m² − 1, m² + 1. If the smallest member…