How to zero-pad numeric variables in zsh (and maybe also bash?)

For reference sake, if you do not have control over the generation of the numeric values, you can do padding with:

% value=314
% echo ${(l:10::0:)value}
0000000314
% echo $value
314

Use the -w flag to seq (in any shell):

$ seq -w 1 10
01
02
03
04
05
06
07
08
09
10