Question

please Explain why 7×11×13+11 is a composite number ?

Answer 1

hi there !

$7 \times 11 \times 13 + 11$
$= 1012$
A composite number is a one which has more than one factor.

using the divisibility rule of 2 which states that for a number to be divisible by 2 , the unit digit must have 0,2,4,6 or 8 in units place .

here , 1012 has 2 in ones place , so it is divisible by 2.

now,

for a number to be divisible by 4 , the units and the tens digit should be divisible by 4
12 is divisible by 4.

so, it is divisible by 4

similarly,
the number is also divisible by 11.


so, it can be said that 7×11×13+11 which is 1012 is a composite number.

Answer 2

= 7×11×13+11
= 11(7*13+1)
=11(91+1)
= 11(92)
Since 92 is a composite no. So 7×11×13+11 is also composite no.


Hope it helps