Question

explain why 2×3×7+7 is composite number

Answer 1

2*3*7+7=49
49 has multiple other than 1 which is 7(7*7) so it is composite

Answer 2

In the given question, 2×3×7+7 can be modify as
= 7 ( 2×3 + 1 )
= 7 ( 7 )
Clearly, it is composite as there are more than two factors than 1 and itself.