Factor
- CBSE · NCERT Class 6, Ch 5 Prime Time
A factor of a number is a whole number that divides it exactly, leaving no remainder, so 3 is a factor of 12.
If a number divides another with nothing left over, it is a factor of that number. Factors are also called divisors. Every number has 1 and itself as factors. Factors come in pairs that multiply to give the number.
Factor and multiple are two views of one fact. 3 is a factor of 12, and 12 is a multiple of 3.
A small example
Find all the factors of 100. Look for pairs that multiply to 100:
- 1 × 100 = 100.
- 2 × 50 = 100.
- 4 × 25 = 100.
- 5 × 20 = 100.
- 10 × 10 = 100.
After 10 × 10 the pairs start to repeat, so you can stop. The factors of 100 are 1, 2, 4, 5, 10, 20, 25, 50 and 100. That is nine factors. Is 3 a factor? No, because 100 ÷ 3 leaves 1 over.
A number with exactly two factors is a prime number. A number with more than two is composite.
Why it matters later
Class 10 Chapter 1 breaks numbers into prime factors. This is prime factorisation, and it is how you find the HCF and LCM of two numbers. Listing factors cleanly in Class 6 is the same skill, done by hand.
Sources
Facts last checked against these sources on 30 September 2026.
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