C:\_32>perl -wle "$m = (2**113) - 1; $n = 2; print $m % $n;" 0 #### C:\_32>perl -MPOSIX -wle "$m = (2**113) - 1; $n = 2; print fmod($m, $n);" 1 #### Binary "%" is the modulo operator, which computes the division remainder of its first argument with respect to its second argument. Given integer operands $m and $n: If $n is positive, then "$m % $n" is $m minus the largest multiple of $n less than or equal to $m. If $n is negative, then "$m % $n" is $m minus the smallest multiple of $n that is not less than $m (that is, the result will be less than or equal to zero). If the operands $m and $n are floating point values and the absolute value of $n (that is "abs($n)") is less than "(UV_MAX + 1)", only the integer portion of $m and $n will be used in the operation (Note: here "UV_MAX" means the maximum of the unsigned integer type). If the absolute value of the right operand ("abs($n)") is greater than or equal to "(UV_MAX + 1)", "%" computes the floating-point remainder $r in the equation "($r = $m - $i*$n)" where $i is a certain integer that makes $r have the same sign as the right operand $n (not as the left operand $m like C function "fmod()") and the absolute value less than that of $n. Note that when "use integer" is in scope, "%" gives you direct access to the modulo operator as implemented by your C compiler. This operator is not as well defined for negative operands, but it will execute faster. #### If $n is positive, then "$m % $n" is $m minus the largest multiple of $n less than or equal to $m. .... If the operands $m and $n are floating point values and the absolute value of $n (that is "abs($n)") is less than "(UV_MAX + 1)", only the integer portion of $m and $n will be used in the operation (Note: here "UV_MAX" means the maximum of the unsigned integer type) #### C:\_32>perl -wle "$r = 10384593717069655257060992658440191.0 - (5192296858534827628530496329220095.0 * 2); print $r;" 1 #### C:\_32>perl -wle "$m = (2**113) - 1; $n = 2; print $m % $n;" 0 C:\_32>perl -MPOSIX -wle "$m = (2**113) - 1; $n = 2; print fmod($m, $n);" 1 #### C:\>perl -wle "$m = (2**64) - 1; $n = 2; print $m % $n;" 0 C:\>perl -MPOSIX -wle "$m = (2**64) - 1; $n = 2; print fmod($m, $n);" 1 #### C:\_32>perl -wle "$m = (2**53) - 1; $n = 2; print $m % $n;" 1 C:\_32>perl -MPOSIX -wle "$m = (2**53) - 1; $n = 2; print fmod($m, $n);" 1