This algorithm made just for hobby. You can use it with any number and it will get you number + 1.
$onePlus = new PlusOneAlgorithm("99999999999999999999999999999999")
$onePlus->calculate();
Result is -> 100000000000000000000000000000000
1 -> 2
2 -> 3
9 -> 10
999 -> 1000
1000 -> 1001
998 -> 999
756 -> 757
9999999999999999999999999999999999999999999999999999999999999999 -> 10000000000000000000000000000000000000000000000000000000000000000