I'm a Perl novice and hope this is a proper channel for a simple question. Why does the following decrement incorrectly below 10? It works with $i -- or $i -= .5. This is part of a larger script and I've made a workaround, but I'm still curious. use Math::Complex; for ($i = 13; $i >= 1; $i -= .1) { print"$i\n"; } 11 10.9 10.8 10.7 10.6 10.5 10.4 10.3 10.2 10.1 10 9.90000000000001 9.80000000000001 9.70000000000001 9.60000000000001 9.50000000000001 9.40000000000001 9.30000000000001 9.20000000000001 9.10000000000001 9.00000000000001