What is the 9th prime number?
The 9th prime number is 23. The next prime is 29 (a gap of 6) and the one before is 19.
Position
Pick any whole number from 1 to 10,000.
How to work it out
- 1
List the primes in order: 2, 3, 5, 7, 11, 13, ā¦ The 9th one is 23.
- 2
23 is prime because no prime up to ā23 ā 4.80 divides it.
- 3
The primes are spread thinner as numbers grow: by the prime number theorem the 9th prime is close to 9 Ć ln(9) ā 20, and here it is 23.
- 4
23 has no twin: neither 21 nor 25 is prime.
Primes around the 9th
| Position | Prime | Gap from the previous |
|---|---|---|
| 6 | 13 | 2 |
| 7 | 17 | 4 |
| 8 | 19 | 2 |
| 9 | 23 | 4 |
| 10 | 29 | 6 |
| 11 | 31 | 2 |
| 12 | 37 | 6 |
Questions
What is the 9th prime number?
23.
Which prime number is 23?
23 is the 9th prime number.
What is the sum of the first 9 primes?
100.