NUMBER OF 3 DIGIT NUMBERS DIVISIBLE BY 7

From 1 to 100, if you want to find number of numbers which are divisible by 7, how will you find?

Step 1 :

Divide 100 by 7

¹⁰⁰⁄₇ = 14.29

Step 1 :

When we divide 100 by 7, we get 14.29.

We should not round this result to the next integer or previous integer (that is 15 or 14).

We have to consider the largest integer contained in 14.29.

That is 14.

From 1 to 100, number of numbers divisible by 7 is 14.

Be careful! the above mentioned method will work only if you take the numbers from 1.

Note :

Whenever we want to find number of numbers which are divisible by k from 1 to a particular number x, we have to divide x by k.

To get the number of numbers divisible by k from 1 to x, we have to consider the largest integer contained in the result of ˣ⁄k.

In the result of ˣ⁄k, we should not round to the nearest/next integer. For example, we should not round 14.9 to 15.

Question :

How many three digit numbers are divisible by 7?

Answer :

Step 1 :

The smallest three digit number is 100.

The largest three digit number is 999.

Step 2 :

Let us find number of numbers divisible by 7 from 1 to 999.

Divide 999 by 7 ----> ⁹⁹⁹⁄₇ = 142.71

Therefore number of numbers divisible by 7 from 1 to 999 is 142.

Step 3 :

Let us find number of numbers divisible by 7 from 1 to 99.

Divide 99 by 7 ----> ⁹⁹⁄₇ = 14.14

Therefore number of numbers divisible by 7 from 1 to 99 is 14.

Step 4 :

Number of numbers divisible by 7 (1 to 999) = 142.

Number of numbers divisible by 7 (1 to 99) = 14.

Number of numbers divisible by 7 (100 to 999) :

= 142 - 14

= 128

Therefore, number of three digit numbers (100 to 999) which are divisible by 7 is 128.

This is how to we have to find number of 3 digit numbers divisible by 7.

The concept explained in the above problem will not only be helpful to find number of 3 digit numbers divisible by 7, it can also be applied to find number of 3 digit numbers which are divisible by any n umber.

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NUMBER OF 3 DIGIT NUMBERS DIVISIBLE BY 7

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