Is 2 a prime number?
2 is a prime number, because nothing up to its square root (about 1) divides it, so its only factors are 1 and 2.
Checking 2 for primality, divisor by divisor
| Try | Into | Gives | Verdict |
|---|---|---|---|
| 2 | 2 | 1 remainder 0 | divides exactly |
You only need to test primes up to the square root of 2, about 1: if 2 had a factor bigger than that, its partner would be smaller and would already have been found.
The quick checks first
- Divisible by 2? Yes: the last digit is even.
- Divisible by 3? No: the digit sum is 2.
- Divisible by 5? No: the last digit is 2.
- Divisible by 9? No: the digit sum is 2.
- Divisible by 10? No: the last digit is 2.
All the factors of 2
1, 2 (2 factors)
The primes near 2
The prime before 2 is none; the prime after it is 3.
🧮 Calculator
The answer appears here, with the working in words.
✏️ Five questions, answers hidden
1. Is 3 prime?
Answer: yes
2. Is 4 prime?
Answer: no
3. What is the smallest prime factor of 6?
Answer: 2
4. List the primes between 10 and 30.
Answer: 11, 13, 17, 19, 23, 29
5. Up to which number do you need to test divisors for 7?
Answer: the square root, about 2
📚 The class this belongs to
Prime and composite numbers are taught in Grade 4 and 5 in the US, Year 5 in the UK (KS2), Class 5 and 6 in CBSE and Year 5 and 6 in Australia.
If this page is the homework and the method is not sticking, that is what a 1-on-1 class fixes: one tutor with a master's degree, one child, on a shared whiteboard, in your time zone, about US$10 to $13 an hour. How 1-on-1 online tutoring works.