Practice Arena

Python Coding Challenges

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925 challenges 556 easy 323 medium 46 hard
Math & Number Theory easy

Amicable Numbers Check

Write a function that checks if two numbers are an amicable pair by comparing sums of proper divisors.

divisors arithmetic math
+10 pts 15m
Math & Number Theory easy

Armstrong Number Check

Implement a function that checks if a given integer is an Armstrong number.

arithmetic number-theory validation
+10 pts 10m
Math & Number Theory easy

Multiply without multiply

Write a function that multiplies two integers using only addition, subtraction, and bit shifts — no * operator.

multiplication bit-manipulation arithmetic
+8 pts 12m
Math & Number Theory medium

Zeller Congruence Weekday

Implement a function that returns the weekday name for a given date using Zeller's congruence.

math modular-arithmetic date
+20 pts 20m
Math & Number Theory easy

Modular Inverse

Implement a function that returns the modular inverse of a modulo m, or -1 if it does not exist.

modular-arithmetic euclid math
+10 pts 15m
Math & Number Theory easy

Chinese Remainder Theorem

Solve a system of congruences with pairwise coprime moduli using the Chinese Remainder Theorem.

modular arithmetic crt coprime
+10 pts 15m
Math & Number Theory medium

Multinomial coefficient

Write a function to compute the multinomial coefficient efficiently for given nonnegative counts.

combinatorics math division
+20 pts 20m
Math & Number Theory medium

Binomial Coefficient

Implement a function to compute binomial coefficients modulo 10^9+7 for n up to 10^5.

modular-arithmetic combinatorics dynamic-programming
+25 pts 25m

Showing 1–8 of 8 challenges · Math & Number Theory

Math & Number Theory — Python coding challenges

What you will find here

This page lists math & number theory challenges — real Python problems you solve in the browser IDE with instant test feedback. Each challenge includes a clear brief, starter code, and automated checks.

Challenges vs tutorials and quizzes

Challenges test what you can build under constraints. For guided teaching, use our Python tutorials. For quick checks, try quizzes or copy snippets from code samples.