The MOD and REM functions return the arithmetic modulo (remainder) of two numeric expressions.
Both expression1 and expression2 should evaluate to numeric expressions or a runtime error will occur.
The modulo is calculated as the remainder of expression1 divided by expression2. If
expression2 evaluates to 0, then the value of expression1 is returned.
FOR I = 1 TO 10000
IF MOD(I, 1000) = 0 THEN CRT "+":
displays a "+" on the screen every 1000 iterations.