Question

If n is a natural number then we define n! (pronounced as factorial n) to be the product $n\times (n-1)\times (n-2)\times ....\times 2\times 1$For example 4! = 4 x 3 x 2 x 1 = 24 If 6! = $a!\times b!$ where a > 1 and b > 1 then a + b is

• A. $8$
• B. $7$
• C. $6$
• D. $5$

Answer 1

The correct option is A $8$

$6!=3!\times 2!$
$3!=3\times 2\times 1$
$2!=2\times 1$
$3!+2!=(3\times 2\times 1)+(2\times 1)$
$=6+2=8$