Question

find the sum of all two digit natural numbers which are divisible by 4

Answer 1

ANSWER IS
The two digits numbers which are divisible by 4 are 12,16,20,......96 in AP. Sn = n/2(2a+(n -1)d) Here a = 12 , d = 4. tn = a + (n - 1) d 96 = 12 + ( n - 1) 4 84 = ( n - 1) 4 n - 1 = 21 ∴n = 22 S22 = (22/2) (2×12 + (22 -1)4) S22 = 11×[ 24 + 84] S22 = 11×[ 24 + 84] ∴S22 = 1188.
mrk as branlist

Answer 2

The two digits numbers which are divisible by 4 are

12,16,20,......96  in AP.

Sn = n/2(2a+(n -1)d)

Here a = 12 , d = 4.

tn = a + (n - 1) d

96 = 12 + ( n - 1) 4

84 = ( n - 1) 4

n - 1 = 21

∴n = 22

S22 = (22/2) (2×12 + (22 -1)4)

S22 = 11×[ 24 + 84]

S22 = 11×[ 24 + 84]

∴S22 = 1188.

i hope its right