Question

11. How many three-digit numbers are divisible by 7?
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Answer 1

Answer:

The first 3-digit number which is divisible by 7 is 105

The last 3-digit number which is divisible by 7 is 994

The list of 3-digit numbers divisible by 7 are

105, 112, 119,…..994 which forms an A.P

Consider a formula

T(n) = a + (n – 1)d

Where

a = 105

d = 7

T(n) = 994

994 = 105 + (n – 1)7

889 = 7n – 7

7n = 896

n = 128

∴ There are 128 3-digits number which are divisible by 7.

Answer 2

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128

∴ There are 128 3-digits number which are divisible by 7.