Question

explain why 7×11×13+13 and 7×6×5×4×3×2×1+5 are composite numbers​

Answer 1

Given 7×11×13+13

=13×(7×11+1)=3×78 

This number is multiple of two integers.Hence it has more than two factors.Hence it is a composite number.

similarly in

7×6×5×4×3 ×2×1+5   

=5(7×6×4×3 ×2×1+1)=5×1009   

This number is multiple of two integers.Hence it has more than two factors.Hence it is a composite number.