Question

Find the sum of composite numbers between $8$ and $12$.

Answer 1

Find the sum:

The numbers having more than two factors are called Composite numbers.

Numbers between $8$ and $12$ are $9,10,11$.

Factors of $9$ are $1,3,9$.

Factors of $10$ are $1,2,5,10$.

Factors of $11$ are $1,11$.

Number $9,10$ have more than two factors.

So, composite numbers between $8$ and $12$ are $9,10$.

Hence, the sum of composite numbers between $8$ and $12$ is $9+10=19$.