Question

Help me please this is confusing!

Answer 1

773

Explanation:

prime numbers from 1 - 10

2,3,5,7.

The first digit should be 7.

7+5+3 = 15

7+3+3= 13 prime

7+5+2= 14

7+2+2= 11 prime

7+2+3= 12

7+5+5= 17 prime

7+7+7= 21

7+7+2= 16

7+7+3=17 prime and itself is prime

7+7+5=19 prime but 775 itself is not prime