Question

Hiw many numbers between 400 to 700 are divisible by either 9,or 11?

Answer 1

Let’s first find the numbers divisible by 9 between 400 to 700.

For this, find the first and last number divisible by 9 between 400 to 700.

Thus, we get

First number=405 and last number=693

Now, use the formula of A.P. i.e. l=a+(n-1)d

Where, l=693, a=405, d=9.

Thus,

693=405+(n-1)9

n=33

Similarly, finding the numbers divisible by 11 and 99 between 400 to 700.

For 11 we get n=27

For 99 we get n=3

Thus, the total numbers between 400 to 700 are 57.

Answer 2

Thank you for asking this question:

We will assume as the least no divisible by 9 is 405

And the most is 693

So AP will be formed

405,414,423..........................693

The formula for nth term is given by:

an=a+(n-1)d

So, 693=405+(n-1)9

288=(n-1)9

32=n-1

So, n=33

If there is any confusion please leave a comment below.