Question

Express 25 as sum of two consecutive numbers.

• A. (12, 13)
• B. (13, 14)
• C. (10, 11)
• D. (14, 15)

Answer 1

The correct option is A (12, 13)

25 is square of 5.
Square of any odd number n can be expressed as sum of two consecutive numbers.
$n^2=\frac{n^2-1}{2}+\frac{n^2+1}{2}$...(i)
$5^2=25$
Here,
n = 5
Substituting 5 in (i)
$5^2=\frac{5^2-1}{2}+\frac{5^2+1}{2}25=12+13$
Therefore, 25 can be expressed as sum of 12, 13.