Without doing the actual addition, find the sum of:

1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19 + 21 + 23

Without doing the actual addition, find the sum of:

1 + 3 + 5 + 7 + 9 + …………… + 39 + 41

Write three sets of Pythagorean triplets such that each set has numbers less than 30.

A Pythagorean triplet has one number equal to 6. The Pythagorean triplet are :

1. 5, 6, 7

2. 6, 7, 8

3. 4, 6, 8

4. 6, 8, 10