Here are some numbers:
4
6 7
15
21
Which number is a prime number?

7

Step-by-step explanation:

Prime numbers have a factor of 1 and itself.

4 is not prime because it has a factor of 2.

6 is not prime because it has factors 2 and 3.

7 is prime, it has 1 and 7 as its factors.

15 is not prime, it has factors of 3 and 5.

21 is not prime, it has factors of 3 and 7.

The only prime number from the list is 7, because the only factors it has is 1 and itself.

idk

step-by-step explanation:

i don't know

fist on the left goes with the third on the right. second on the left goes with the fourth on the right. third on the left goes with the second on the right. the fourth on the left goes with first on the right