(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)
gmp_gcd — Calculate GCD
gmp_gcd(GMP|int|string $num1, GMP|int|string $num2): GMP
Calculate greatest common divisor of num1 and num2. The result is always positive even if either of, or both, input operands are negative.
num1 A GMP object, an int, or a string that can be interpreted as a number following the same logic as if the string was used in gmp_init() with automatic base detection (i.e. when base is equal to 0).
num2 A GMP object, an int, or a string that can be interpreted as a number following the same logic as if the string was used in gmp_init() with automatic base detection (i.e. when base is equal to 0).
A positive GMP number that divides into both num1 and num2.
Example #1 gmp_gcd() example
<?php
$gcd = gmp_gcd("12", "21");
echo gmp_strval($gcd) . "\n";
?> The above example will output:
3
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https://www.php.net/manual/en/function.gmp-gcd.php