What is the composite number between 20 and 40?

1 Answer
George C.
Nov 14, 2016

All of the following are composite:

20, 21, 22, 24, 25, 26, 27, 28, 30, 32, 33, 34, 35, 36, 38, 39, 40

Explanation:

A composite number is any number which has factors apart from 1 and itself.

So most numbers between 20 and 40 are composite:

20 = 2xx2xx5

21 = 3xx7

22 = 2xx11

24 = 2xx2xx2xx3

25 = 5xx5

26 = 2xx13

27 = 3xx3xx3

28 = 2xx2xx7

30 = 2xx3xx5

32 = 2xx2xx2xx2xx2

33 = 3xx11

34 = 2xx17

35 = 5xx7

36 = 2xx2xx3xx3

38 = 2xx19

39 = 3xx13

40 = 2xx2xx2xx5

The only prime numbers (having no factors apart from 1 and themselves) between 20 and 40 are: 23, 29, 31, 37.

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