Python abs(), divmod(), and pow()

Basic

Some numeric tasks have small, dedicated built-ins. abs() gives an absolute value, divmod() returns quotient and remainder together, and pow() performs exponentiation and can also perform modular exponentiation.

The Numbers lesson already teaches ordinary arithmetic operators and round(). This lesson focuses only on these three built-ins and the distinct problems they solve.

abs(): get an absolute value

abs(number) returns the absolute value of a number. For real numbers, that means the non-negative magnitude. For a complex number, it returns the number's magnitude.

divmod(): get quotient and remainder together

divmod(a, b) returns a pair containing the quotient and remainder from integer-style division. For integers, it is equivalent to the pair (a // b, a % b).

Negative operands follow Python's floor-division rules

divmod() follows the same floor-division and remainder rules as // and %. The identity q * b + r == a helps you interpret the returned pair.

pow(): exponentiation

pow(base, exp) performs exponentiation. With two arguments it has the same arithmetic meaning as base ** exp.

pow() with a modulus

pow(base, exp, mod) computes the power and then reduces the result modulo mod. For integer arguments, this form is useful when you need a modular result without first materializing the full power.

A modular inverse

For integer arguments, Python also allows a negative exponent in the three-argument form when the base has an inverse modulo mod. For example, the result below is a value whose product with 3 leaves remainder 1 modulo 11.

Choosing the right built-in

Use abs() when you need magnitude, divmod() when you need quotient and remainder as a pair, and pow() when exponentiation is the operation. Use the three-argument form of pow() when the modulus is part of the problem.

Quick check

result = ?(29, 6)