Question

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

Answer 1

Heya☺

They are composite no. because they have more than 2 prime no. as their factor .
✌✌

Answer 2

7*11*13+13
= 13(7*11*1+1)
= 13(77+1) = 13*78 = 13*2*39

 7×11×13+13 has more than two prime factors so, it is composite number.

now, 7*6*5*4*3*2*1+5
 = 5 (7*6*4*3*2+1)
 = 5(1008+1) = 5*1009 = 5*1009*1

Similarly  7*6*5*4*3*2*1+5  has more than two prime factors so, it is composite number