" 17.Explain why "7times11times13+13" is composite number? "

Explain why: 7xx11xx13xx15+15 is a composite number.

Explain why 5 x 7 x 13 + 13 is a composite number

7xx11xx13+13 is a composite number. Why ?

Explain why: 11xx13xx17+17 is a composite number.

Explain why 5xx11xx12+12 is a composite number.

Explain why 3 xx 5xx 7 xx + 7 is a composite number

Explain why 31xx17xx13xx12+31xx17xx5 a composite number.

Explain why 3 xx 5 xx 7 +7 is a composite number.

Explain why 3 xx 5 xx 7 +7 is a composite number.

Explain why (7 times 11 times 13)+13 " and " (7 times 6 times 5 times 4 times 3 times 2 times 1)+5 are composite numbers.