Question

Without adding, find the sum. (i) 1 + 3 + 5 + 7 + 9 (ii) 1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 +19 (iii) 1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19 + 21 + 23​

Answer 1

i) Total consecutive odd numbers = 5

Thus n = 5

Therefore sum = n2

= 5*5 = 25

ii)

Total consecutive odd numbers = 10

Thus n = 10

Therefore sum = n*n

= 10*10 = 100

iii)

Total consecutive odd numbers = 12

Thus n = 12

Therefore sum = n*n

= 12*12 = 144

Answer 2

You need to calculate the all sum....... by calculator.