C:\>perl -le "printf '%.0f', 2e25;"
20000000000000001811939328
C:\>perl -le "printf '%.0f', 20e24;"
19999999999999997516972032

##</code><code>##

$ perl -le 'printf "%.0f\n", 2e25;'
20000000000000001811939328
$ perl -le "printf '%.0f', 20e24;"
19999999999999997516972032