Question

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

Answer 1

You should count all numbers . for exp 1 St Q 1+3+5+7+9 there are 5 digits then we find square of 5=25 And note that this property works only on odd nos

Answer 2

Heya ✋

Let see your answer !!!!

(i) 1 + 3 + 5 + 7 + 9
$= 5 ^{2} \\ = 25$
(ii) 1 + 3 + 5 + 7 + 9 + 11 + 13 + 15
$= 8 ^{2} \\ = 64$

(iii) 1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19 + 21 + 23
$12 ^{2} \\ = 144$






Thanks :))))