An integer is a signed whole number: 1, 3, -7.
Some languages allow integers only up to a fixed size, say 32 bits (about +/- 2147483647). Scheme allows integers of any size; the larger ones are sometimes called bignums (short for ``big numbers'').
A rational number is a quotient of two integers: 1, 1/3 . The rationals include the integers as a subset.
Integers and rationals are exact numbers because their values are represented exactly in the computer. Operations on exact numbers produce exact results.
Operations on integers and rationals include: + - * /
- can take one argument or two: (- x) or (- x y).
max | maximum of its arguments: | (max 3 7) = 7 |
min | minimum of its arguments: | (min 3 7) = 3 |
abs | absolute value: | (abs -3) = 3 |
modulo | remainder after division: | (modulo 7 3) = 1 |
gcd | greatest common divisor: | (gcd 42 24) = 6 |
lcm | least common multiple: | (lcm 12 15) = 60 |
expt | raises a number to a power: | (expt x 3) = x^3. |