Coding interviews-এ common mathematical patterns:

Prime checking
Factorial
Fibonacci
GCD
LCM
Modulo
Digits
Probability

Example: GCD

Euclidean algorithm:

def gcd(a, b):
    while b:
        a, b = b, a % b
    return a

Example:

gcd(48, 18)

Steps:

48 % 18 = 12
18 % 12 = 6
12 % 6 = 0

Answer:

6

Time roughly:

$$O\left. \left( \log\left. \left( \min\left. (a,b) \right. \right) \right. \right) \right.$$