Factors of 1
The factors of 1 are 1. 1 is neither prime nor composite. Prime factorisation: 1.
All 1 factors of 1
1
A factor divides 1 exactly, with no remainder. Every factor has a partner: the pairs below multiply to 1. The negative factors are -1, because a negative times a negative is positive.
Factor pairs of 1
| Pair | Product |
|---|---|
| 1 × 1 | 1 |
Stop at the square root (1): every pair after that is one you already have, the other way round.
Prime factorisation of 1: 1
1 has no prime factors.
So 1 = 1.
How to find the factors of 1
- Start with 1 and 1: every number has those two.
- Test 2, 3, 4, … up to the square root of 1, which is about 1.
- Each time a number divides exactly, write it down with its partner (the quotient).
- Use the divisibility rules to skip work: by 2 no (the last digit is odd); by 3 no (the digit sum is 1); by 5 no (the last digit is 1).
- Put the list in order: 1.
🧮 Calculator
The answer appears here, with the working in words.
✏️ Five questions, answers hidden
1. List the factors of 2.
Answer: 1, 2
2. Write the prime factorisation of 2.
Answer: 2
3. How many factors does 1 have?
Answer: 1
4. What is the largest factor of 1 other than itself?
Answer: none; 1 has only itself
5. Is 3 prime or composite?
Answer: prime
📚 The class this belongs to
Factors are taught in Grade 4 and 5 in the US, Year 5 and 6 in the UK, Class 4 to 6 in CBSE (NCERT Class 6, Playing with Numbers) and Year 5 and 6 in Australia.
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