Question

29. The total numbers from 1 to 400 which are
divisible either by 3 or by 7 are​

Answer 1

Answer:

May I assume you mean both 3 and 7? Then we are looking for multiples of 21.

The smallest is 21 = 1 x 21.

The largest is 300 = 19 x 21.

So there are 19 of them.

If you mean divisible by 3 or 7, then we are looking to add the number of multiples of 3 and multiples of 7 and then subtracting the multiples of both (so we do not count them twice).

Smallest multiple of 3 is 3 = 1 x 3. Largest multiple of 3 is 399 = 133 x 3. There are 133 of them.

Smallest multiple of 7 is 7 = 1 x 7. Largest multiple of 7 is 399 = 57 x 7. There are 57 of them.

133 + 57 - 19 = 171.

Answer 2

Step-by-step explanation:

7×3=21

7×9=63

52×3=156

21×3=63