Question

(1) Find the sum of all two digit natural numbers which are divisible by 4.​

Answer 1

Answer:

The two digits numbers which are divisible by 4 are

12,16,20,......96  in AP.

Step-by-step explanation:

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.