Math & Numbers Facts for Kids
Mind-bending number facts
Blaise Pascal and Pierre de Fermat invented probability theory in 1654 while exchanging letters about a gambling problem. Their work on how to fairly split prize money became the foundation for insurance, weather forecasting, and statistics.
In exponential growth, the time required to double is always the same β regardless of where you start. If a bacteria colony doubles every 20 minutes, it doubles whether there are 10 bacteria or 10 billion.
Angles greater than 180 degrees, called reflex angles, are real and measurable. A full turn is 360 degrees, and reflex angles are between 180 and 360 degrees β like the larger part of a slice taken from a pie.
The number 1,729 is called the Hardy-Ramanujan number. When Hardy visited the ill Ramanujan in hospital and mentioned arriving in taxi number 1,729, Ramanujan instantly replied it was interesting β it's the smallest number expressible as the sum of two cubes in two different ways: 1Β³+12Β³ and 9Β³+10Β³.
Probability is always a number between 0 and 1. A probability of 0 means something is impossible, and 1 means it is certain. The probability of rolling any number on a six-sided die is 1/6, since there are six equally likely outcomes.
To check if two fractions are equal, multiply the top of each by the bottom of the other. If the two results match, the fractions are equivalent. For example, 2/3 and 4/6: 2Γ6 = 12, and 3Γ4 = 12. They're equal.
Penrose tiling covers a flat surface with two diamond shapes that never repeat in a regular pattern β they're aperiodic. Physicist Roger Penrose discovered them in 1974, and the same patterns were later found in quasicrystals, a real material in nature.
There are three common types of average: mean (add all numbers and divide), median (the middle value), and mode (the most frequent value). For the set 1, 2, 2, 3, 100, they give very different results β mean β 21, median = 2, mode = 2.
A Sophie Germain prime is a prime p where 2p + 1 is also prime. For example, 11 is a Sophie Germain prime because 2 Γ 11 + 1 = 23, which is also prime. They are named after French mathematician Sophie Germain, who studied them in the 1800s.
A cone has exactly one-third the volume of the cylinder that fits perfectly around it. Archimedes discovered this relationship, and you can verify it by filling a cone with water and pouring it into the matching cylinder three times.