=13(7×11 1)
=13(77 1)
=13×78
=13×13×3×2
since it has more than two factors (13,3,2,1,13)×78 I.e 1014. It is a composite number
Now,7×6×5×4×3×2×1 5
=5(7×6×5×4×3×2×1 1)
=5(1008 1)
=5(1009)
Since it has more than two factors (5,1009,1,5×1009 I.e 5045)
It is a composite number.
Written on Sept. 8, 2020, 4:37 p.m.