Try the divisibility rules:
A number is divisible by 2 if the last digit is even.
(a) ..1 NO
(b) ..3 NO
A number is divisible by 3 if the sum of the digits is divisible by three.
(a) 2+3+1=6/3=2 with no remainder
(b) 3+9+3=12/3=4 with no remainder
Can you make the conclusions?
31. Determine whether each of the following numbers is prime or composite.
(a) 231 (b) 393
1 answer
1 answer