Question

The sum of all two digit odd numbers is ______.

Options

• 2575

• 2475

• 2524

• 2425

Answer 1

The sum of all two digit odd numbers is 2475.

Explanation:-

All two digit odd numbers are 11,13,15,… 99, which are in A.P.

Since there are 90 two digit numbers of which 45 numbers are odd and 45 numbers are even

∴ Sum = `45/2`[11 + 99]

= `45/2` × 110

= 45 × 55

= 2475