I am trying to a do a big calculation for example:
$a = 50000 * 1000000000000000000;
the result its 5.0E+22 in php
how can I convert it or print it as "50000000000000000000000" as string, cause it's not possible in int?
This number is actually too large for an integer representation in PHP and converting to a float won't get the precision for this number. When doing math that requires huge numbers or accurate precision, it's best to use bc math with strings.
echo bcmul("50000", "1000000000000000000");
// prints "50000000000000000000000"