NCERT Solutions for Class 10 Maths Chapter 5

Important NCERT Questions

Arithmetic Progression

NCERT Books for Session 2022-2023

CBSE Board and UP Board Others state Board

EXERCISE 5.2

Page No:106

Questions No:13

# How many three-digit numbers are divisible by 7?

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Three digit numbers divisible by 7 : 105, 112, 119, . . . , 994

Let the total number of these numbers be n.

Here, a = 105 and d = 112 – 105 = 7. To find: n, where a_n = 994.

Given that: a_n = a + (n – 1)d = 994

⇒ 105 + (n -1)(7) = 994

⇒ 7(n -1) = 889

⇒ n – 1 = 888/7 = 127 ⇒ n = 128

Hence, there are 128 three digits numbers which are divisible by 7.