The factors of a number can be found by two methods:

- Using division

- Using multiplication

**1. Factorization using division:**

In this method, start dividing the given number by $1$, $2$, $3$ and so on to determine which number can divide the given number exactly without giving any remainder. When the remainder is zero, both the divisor and the quotient are the factors of the number. When u reach a point where the factors begin to be repeated, there will not be any further factors.

For example find the factors of $20$

$20 \div 1 = 20$ … $1$ and $20$ are factors of $20$

$20 \div 2 = 10$ … $2$ and $10$ are factors of $20$

$20 \div 3 =$ Leaves reminder

$20 \div 4 = 5$ … $4$ and $5$ are factors of $20$

$20 \div 6 =$ Leaves reminder

$20 \div 7 = $ Leaves reminder

$20 \div 8 = $ Leaves reminder

$20 \div 9 = $ Leaves reminder

$20 \div 10 = 2$ … $10$ and $2$ are factors of $20$

Stop here, since $10$ and $2$ are already the factors.

$\therefore$ the factors of $20$ are $1$, $2$, $4$, $5$, $10$.

**2. Factorization by multiplication:**

All the numbers used to build a product are the factors of the product.

For example find the factors of $18$.

$1 \times 18 = 18$

$2 \times 9 = 18$

$3 \times 6 = 18$

$\therefore$, the factors of $18$ are $1, 2, 3, 6, 9$ and $18$.