Math & Numbers Facts for Kids
Mind-bending number facts
Logarithms are a tool for working with very large numbers. The Richter scale for earthquakes and the decibel scale for sound both use logarithms β each step up the scale represents a tenfold increase, not a simple addition.
If 10 people all shake hands with each other, how many handshakes are there? The answer is 45 β not 90, because each handshake is shared between two people. This type of counting problem leads to triangular numbers.
Prime numbers become rarer the higher you count. Among numbers up to 100, about 25% are prime. Among numbers near 1 billion, fewer than 5% are prime. The Prime Number Theorem precisely describes this thinning out.
An isosceles triangle has two sides that are equal in length, and the two angles opposite those sides are also equal. Ancient architects used this property when designing symmetric arches and rooflines.
The SierpiΕski triangle is a fractal created by repeatedly removing the middle triangle from an equilateral triangle. After infinite steps, the shape has zero area but infinite perimeter β a mind-bending mathematical result.
You cannot divide by zero β it is undefined in mathematics. If dividing by zero gave an answer, you could prove that 1 = 2, which would break the entire number system. Calculators simply display an error when you try.
Mathematicians have a whole branch of study dedicated to knots. Knot theory started in the 1800s and today is used to understand how DNA tangles and untangles itself inside cells.
The area of a triangle is always half the base times the height. This works for any triangle β you can prove it by fitting two copies of the triangle together to form a rectangle or parallelogram.
In many real-world data sets β populations, stock prices, river lengths β the number 1 appears as the first digit about 30% of the time, not 11% as you might expect. This surprising pattern is called Benford's Law and is used to detect financial fraud.
A square has 4 lines of symmetry, a regular hexagon has 6, and a circle has infinitely many. The more lines of symmetry a shape has, the more 'balanced' it looks, which is why symmetric shapes appear in art and architecture worldwide.