Explain why 7×11×13+13 and 7×6×5×4×3×2×1+5 are composite number. (Real numbers)

Explain why 7×11×13+13 and 7×6×5×4×3×2×1+5 are composite numbe

1.	Explain why 7×11×13+13 and 7×6×5×4×3×2×1+5 are composite number. (Real numbers)
Answer» Numbers are of two types - prime and composite.Prime numbers can be divided by 1 and only itself, whereas composite numbers have factors other than 1 and itself.It can be observed that7 × 11 × 13 + 13 = 13 × (7 × 11 + 1)= 13 × (77 + 1)= 13 × 78= 13 ×13 × 6The given expression has 6 and 13 as its factors.Therefore, it is a composite number.7 × 6 × 5 × 4 × 3 × 2 × 1 + 5= 5 ×(7 × 6 × 4 × 3 × 2 × 1 + 1)= 5 × (1008 + 1)= 5 ×10091009 cannot be factorized furtherTherefore, the given expression has 5 and 1009 as its factors.Hence, it is a composite number.