[discuss tcl variable type of int - how much data fits in that amount, when does tcl use it, when does it benefit the user, etc.]
The expr-function int returns the 32-bit integer value of a number.
% expr {int(- pow(2,31))}
-2147483648
% expr {int(pow(2,31)-1)}
2147483647
% expr {int(pow(2,31))}
integer value too large to represent
%