Q1 of 67 Page 86

Find the sum 1 + 3 + 5 + … + 51 (the sum of all odd numbers from 1 to 51) without actually adding them.

Total terms =

= 26

As we know, that sum of first n odd natural numbers is n²

⇒ Sum of above digits = 26²

= 676

Write 3-digit numbers ending with 0, 1, 4, 5, 6, 9, one for each

digit, but none of them is a perfect square.

Find numbers from 100 to 400 that end with 0, 1, 4, 5, 6 or 9, which are perfect squares.

Express 144 as a sum of 12 odd numbers.

Find the 14^th and 15^th triangular numbers, and find their sum. Verify the Statement 8 for this sum.

Questions · 67

5. Squares, Square-Roots, Cubes and Cube-Roots

1 2 3 4 5 1 2 3 4 1 1 1 1 2 3 1 1 1 1 1 2 2 2 2 2 2 3 4 5 1 2 3 1 2 3 4 5 6 1 1 1 1 1 2 2 2 3 1 2 2 2 2 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16