PET VIC-20 C64 C16 Plus/4 C128 X16 M65

The MOD (“modulo”) operator solves the remainder of a division, after one number is divided by another.

<dividend> MOD <divisor>

PRINT 5 MOD 2 : REM outputs 1

The above expression evaluates to 1, because 5 divided by 2 has a quotient of 2 and a remainder of 1.

CONST PI = 3.14159
PRINT (2.5 * PI) MOD PI : REM outputs a number equal to PI/2

The following program checks whether a year is a leap year:

DIM in$ AS STRING * 4
DIM year AS WORD
DIM isleap AS BYTE
CONST TRUE = 255
CONST FALSE = 0
INPUT "enter year: "; in$
year = CWORD(VAL(in$))
IF year MOD 4 = 0 THEN
  IF year MOD 100 = 0 THEN
    isleap = (year MOD 400 = 0)
  ELSE
    isleap = TRUE
  END IF
ELSE
  isleap = FALSE
END IF
PRINT year; " is ";
IF NOT isleap THEN PRINT "not ";
PRINT "a leap year."