# Category: Number Theory

## INTERSECTING STICKS/LINES MULTIPLICATION TRICK

As many of you probably know, there are a myriad of ways on coming up on techniques in multiplication. This time, I would like to share one of my favorites – the intersecting sticks/lines...

## 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...

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....

## Kennard’s Ellipsoid Equation

Let us bring the search for math wizard to NCR. Another math quizzer named Kennard Ong Sychingping from De La Salle University-Manila wants to share a problem that can surely twist our brains. He...

## 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,...

## Perpendicular Lines and its Application

Perpendicular lines are two intersecting lines that meet at right angle or exactly 90°. Let’s bring that line now to coordinate plane. In Analytical Geometry, two lines are perpendicular if the product of their slopes...