Factors are numbers that divide exactly into another number without leaving a remainder. A factor is never greater than the number itself.
To find the factors of a number:
- Start with $1$ and the number itself.
- Try dividing the number by increasing integers.
- If there is no remainder, add both the divisor and quotient to your factor list.
- Stop testing once you pass the square root of the number.
Step-by-Step: Factors of 25
Begin with: $$ 1, \quad 25 $$
Try 2:
$$ 25 \div 2 = 12.5 \quad \text{(Not exact)} $$
Try 3:
$$ 25 \div 3 \approx 8.33 \quad \text{(Not exact)} $$
Try 4:
$$ 25 \div 4 = 6.25 \quad \text{(Not exact)} $$
Try 5:
$$ 25 \div 5 = 5 \quad \Rightarrow \text{Add } 5 $$
You now have all the factors: $$ 1, \quad 5, \quad 25 $$
We stop here since: $$ \sqrt{25} = 5 $$
Final Result
The full list of factors of $25$ is: $$ 1, \quad 5, \quad 25 $$
Since $25$ has more than two factors, it is a composite number.
✅ The highest factor other than the number itself is: $$ \boxed{5} $$
Summary
- A factor divides evenly into a number.
- The factors of $25$ are: $$ 1, \quad 5, \quad 25 $$
- Since 25 has more than two factors, it is a composite number, not a prime number.