Question

Example 13. How many three-digit
numbers are divisible by 7?​

Answer 1

Answer:

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

Answer 2

Hi Dear Friend

Your answer (My own answer, not searched in web)

Number divisible by 7

Lowest 3 digit number: (check whether divisible by 7)

100/7 = 14.2857143

101/7 = 14.4285714

102/7 = 14.5714286

103/7 = 14.7142857

104/7 = 14.8571429

105/7 = 15

So it is the lowest 3 digit number divisible by 7

Highest 3 digit number:

999 = 142.714285714

998 = 142.571428571 (997,996,...)

994 = 142

So it is the highest 3 digit number divisible by 7

Hence, the series starts with 105 and end at 994

We need to find the number of terms:

Lets use a formula

T(n) = a + (n – 1) d

Let  a = 105, d = 7,

T(n) = 994

994 = 105 + (n – 1) 7

889 = 7n – 7

7n = 896

n = 128

Therefore there are 128 3 digit number that is divisible by 7

Hope my answer is helpful