Question

find the sum of all numbers divisible by 9 between 250 and 450​

Answer 1

Answer:

250÷9= 27.77

450÷9= 50

Answer 2

Answer :-

• Sequence of numbers which are divisible by 9 between 250 and 450 is 252 , 261 ..... 441.

If we assume that this sequence is in AP,

• a = 252
• aₙ = 441
• d = 261 - 252 = 9.

We know that,

nth term of an AP (aₙ) = a + (n - 1)d

So,

⟶ 441 = 252 + (n - 1)(9)

⟶ 441 - 252 = 9n - 9

⟶ 189 + 9 = 9n

⟶ 198/9 = n

⟶ 22 = n

Now,

Sum of first n terms of an AP (Sₙ) = n/2 [ 2a + (n - 1)d ]

⟶ S₂₂ = 22/2 * [ 2(252) + (22 - 1)(9) ]

⟶ S₂₂ = 11 (504 + 189)

⟶ S₂₂ = 11(693)

⟶ S₂₂ = 7623

∴ The sum of all numbers divisible by 9 between 250 and 450 is 7623.