TOP SECRET BOMB CALCULATION

The first program outputs:
Yield is: 2.6944002417374e+21 (Joule)

The second:
Storing value with incorrect units at ex/emm.pl line 16

So using the typing has found a problem:
$yield = $eff * $mass * $c **3;

Which we can fix, and get:
Yield is: 8987551787368.18 (Joule)