I could be misinterpreting the Square Root line here, but this does the trick for me...

$a=25;
$b=$a**(1/2); # 25^0.5
print $b; # 5
[download]

or with 2

$a=2;
$b=$a**(1/2); #2^0.5
print $b; #1.4142135623731
[download]

Greetz
Beatnik
... Quidquid perl dictum sit, altum viditur.