Question

How many multiples of 4 lie between 10 and 250?

Answer 1

Given numbers: 10 to 250

∴ Multiples of 4 between 10 and 250 are 

First term: 10 + (4 – 2) = 12 

Last term: 250 – 2 = 248 

∴ 12, 16, 20, 24, ….., 248 

a = a₁ = 12; d = 4; a_n = 248 

a_n = a + (n – 1)d 

248 = 12 + (n – 1) × 4 

⇒ (n – 1)4 = 248 – 12 

⇒ n – 1 = 236/4 = 59 

∴ n = 59 + 1 = 60 

There are 60 numbers between 10 and 250 which are divisible by 4.