ทฤษฎีจำนวน เครื่องคิดเลข

List all primes up to any limit. Instant result with formula, examples and step-by-step calculation. Free online calculator.

Divisibility rules for 2 through 13. Instant result with formula, examples and step-by-step calculation. Free online calculator.

Convert numbers between any base 2 to 16. Fast and accurate result with formula, step-by-step method and unit overview. Free tool.

Is a number perfect abundant or deficient?. Instant result with formula, examples and step-by-step calculation. Free online calculator.

Calculate phi(n) - numbers coprime to n. Instant result with formula, worked example and step-by-step solution. No signup required.

Sum of digits and digital root of any number. Instant result with formula, examples and step-by-step calculation. Free online calculator.

Generate the Collatz sequence for any starting number. Instant result with formula, examples and step-by-step calculation. Free online calculator.