in reply to modulus and floating point numbers

Whether it's faster or not you'll have to determine yourself, but it's another way:

use POSIX qw[ fmod ];; print fmod( $_, 100 ) for 12300, 12301, 12399;; 0 1 99

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.