Problems

1 – 12 of 12

Problem Title Likes Solvers Difficulty

Problem 44862. Ratio between sum of primes and sum of factors

Created by: Jesús Zambrano

Tags primes, factors, ratio

Problem 44229. How brilliant are you?

Created by: James

Tags factors, number theory, brilliant

Problem 54144. Factor Digits

Created by: Dyuman Joshi

Tags factors, prime factors

Problem 1804. Fangs of a vampire number

Created by: Andrew Newell

Tags factors, number theory

Problem 656. Calculate Euler's phi function

Created by: Freddy

Tags math, basic matlab, factors

Problem 365. Numbers with prime factors 2, 3 and 5.

Created by: elias GR

Tags primes, factors

398

Problem 1925. Smith numbers

Created by: Sky Sartorius

Tags sum, factors

466

Problem 1825. Find all vampire fangs

Created by: Andrew Newell

Tags factors, number theory

Problem 54680. Determine whether a number is practical

Created by: ChrisR

Tags factors, number theory, sequence

Problem 577. Repopulate the City

Created by: Ned Gulley

Tags factors

Problem 3075. Matrix of Multiplication Facts

Created by: James

Tags matrix, factors, elementary_school_math

Problem 1826. Find vampire numbers

Created by: Andrew Newell

Tags factors, number theory

274

1 – 12 of 12

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Problem Groups

Difficulty Rating

Problem Groups

Problems

Problem 44862. Ratio between sum of primes and sum of factors

Problem 44229. How brilliant are you?

Problem 54144. Factor Digits

Problem 1804. Fangs of a vampire number

Problem 656. Calculate Euler's phi function

Problem 365. Numbers with prime factors 2, 3 and 5.

Problem 1925. Smith numbers

Problem 1825. Find all vampire fangs

Problem 54680. Determine whether a number is practical

Problem 577. Repopulate the City

Problem 3075. Matrix of Multiplication Facts

Problem 1826. Find vampire numbers