Prime numbers between 1 and 30
There are 10 prime numbers between 1 and 30: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29.
How to work it out
- 1
A prime has exactly two factors, 1 and itself. To list them, cross out multiples of 2, then 3, then 5, and so on up to ā30 ā 5.5 (the sieve of Eratosthenes). What is left are the primes.
- 2
That leaves 10 primes between 1 and 30, with a total of 129.
- 3
The biggest gap between neighbouring primes in this range is 6, after 23 (the next prime is 29). There are 4 twin prime pairs (primes 2 apart): (3, 5), (5, 7), (11, 13), (17, 19).
How many primes in each part
| Range | Primes | Share of the numbers |
|---|---|---|
| 1 to 10 | 4 | 40% |
| 11 to 20 | 4 | 40% |
| 21 to 30 | 2 | 20% |
Questions
How many prime numbers are there between 1 and 30?
10.
What is the biggest prime number below 30?
29.
What is the first prime number after 0?
2.