Question

On subtracting first 25 odd numbers from first 30 odd numbers we get _____

(a) 5^2

(b) 375

(c) 5

(d) 275

I had been asked this question in unit test.

The origin of the question is Patterns in Squares of Numbers topic in division Squares and Square Roots of Mathematics – Class 8

Answer 1

Correct option is (c) 5

To elaborate: If we add the first 25 odd numbers, we get 625 (i.e.25^2) and when we add first 30 odd numbers, we get 900 (i.e.30^2). When we calculate the difference between the two, we get 275. Hence 275 is the correct answer and the others are incorrect.