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How many numbers between 100 and 400 are divisible by 7?

Published in Mathematics 1 min read

There are 43 numbers between 100 and 400 that are divisible by 7.

To determine this, we can find the smallest and largest multiples of 7 within the specified range and then calculate the total number of multiples.

  • Smallest multiple of 7 greater than 100: Dividing 100 by 7 gives approximately 14.29. Therefore, the smallest multiple of 7 greater than 100 is 7 * 15 = 105.

  • Largest multiple of 7 less than 400: Dividing 400 by 7 gives approximately 57.14. Therefore, the largest multiple of 7 less than 400 is 7 * 57 = 399.

Now we have an arithmetic progression (AP) with:

  • First term (a) = 105
  • Common difference (d) = 7
  • Last term (l) = 399

To find the number of terms (n) in the AP, we can use the formula:

l = a + (n - 1)d

Substituting the values:

399 = 105 + (n - 1)7

294 = (n - 1)7

42 = n - 1

n = 43

Therefore, there are 43 numbers between 100 and 400 that are divisible by 7.

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