A number n is practical if all smaller numbers can be written as a sum of the proper divisors of n. The number 24 is practical because its proper divisors are 1, 2, 3, 4, 6, 8, and 12 and for example
5 = 4+1, 7 = 4+3, 9 = 6+3, 10 = 8+2, 11 = 8+3, 13 = 12+1, 14 = 12+2, 15 = 12+3, 16 = 12+4,
17 = 12+4+1, 18 = 12+6, 19 = 12+3+4, 20 = 12+8, 21 = 12+8+1, 22 = 12+8+2, 23 = 12+8+3
However, 23 is not practical because its only proper divisor, 1, cannot be repeated in the sum.
Write a function to determine whether a number is practical.
Solve

Solution Stats

25 Solutions

10 Solvers

Last Solution submitted on May 25, 2026

Last 200 Solutions

Problem Comments

Solution Comments

Show comments

Problem Recent Solvers10

Chris Cleveland George Berken Hong Son Lorenzo

Suggested Problems

More from this Author328

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!