Category: Number Theory

The Phi(ϕ) Function

Phi Function is define as the number of positive integers less than or equal to and coprime to the number. The other name is Euler’s Totient Function. The application of this function is used...

Highest Power in the Expansion of n!

How many zeroes at the end ?If is expressed in its prime factorization form, what is the power of ? What is the highest power of 15 in the expansion in ? These are...

The Heads and Legs Paradox

This heads and legs paradox has been famous from grade school to mid-schoolers.  The problem is something about determining the number of animals given the total number of their heads and legs or feet....

Sum of Divisors

In number theory, many formulas exist that we never think of. The first topic I wrote about number theory is to find the number of divisors an integer has. This time let’s talk about...

Test For Divisibilty

Test for divisibility are short ways to determine the factors of a natural number without doing the actual calculation. Divisibility Test for 2: All even numbers are divisible by 2. Example:  4, 24, 98,...