Without adding, find the sum of the following number

1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19 + 21 + 23 + 25

Open in App

Solution

$1 + 3 + 5 . . . . 25$
$a = 1$ it's an AP
$d = 2$
$25 = 1 + (n - 1) 2$
$24 = (n - 1) 2$
$n - 1 = 12$
$n = 13$
Sum $= \frac{n [a + ℓ]}{2} = \frac{13 [1 + 25]}{2}$
$= 13 \times 13$
$= 169$

Suggest Corrections

Similar questions

1 + 3 + 5 + 7 + 9

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

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

1 + 3 + 5 + 7 + 9

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

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

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

Without adding, find the sum:

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

Join BYJU'S Learning Program