Search for a tool
Previous Prime Number

Tool to search for prime numbers less than a number, or the nth previous prime number of a given number.

Results

Previous Prime Number -

Tag(s) : Arithmetics, Mathematics

dCode and you

dCode is free and its tools are a valuable help in games, puzzles and problems to solve every day!
You have a problem, an idea for a project, a specific need and dCode can not (yet) help you? You need custom development? Contact-me!

Team dCode read all messages and answer them if you leave an email (not published). It is thanks to you that dCode has the best Previous Prime Number tool. Thank you.

# Previous Prime Number

## Previous Prime Number Search

Tool to search for prime numbers less than a number, or the nth previous prime number of a given number.

### How to calculate the previous prime number?

No mathematical formula is used to automatically calculate the prime number preceding any number. dCode perform primality tests on numbers below the requested number until a prime number is found.

Example: The largest prime number that precedes 100 is 97

Example: The 10th prime number preceding 1000 is 937 (so there are 9 prime numbers between 938 and 999)

The number must be a positive real number.

### How to find greatest primes with n digits ?

The first prime number preceding $$10^n$$ is a number with $$n$$ digits which is the greast n-digit prime number.

Example: 7, 97, 997, 9973, 99991, etc.

### What are twin primes numbers?

A prime number and the previous prime number are twins primes when their difference equals 2.

Example: 11 and 13 are called twins primes as 13-11 = 2.