**Early article(s) :** 8 Super Fun Facts about Maths**1. A pizza that has radius “z” and height “a” has volume Pi × z × z × a.**

Because the area of a circle is Pi multiplied by the radius squared (which can be written out as Pi × z × z). Then you multiply by the height to get the total volume.

**2. The word hundred** is derived from the word “hundrath”, which actually means 120 and not 100.

**3. In a room of just 23 people there’s a 50% chance** that two people have the same birthday.

It’s called the Birthday Problem. In a room of 75 there’s a 99% chance of two people matching.

**4. 111,111,111 × 111,111,111** = 12,345,678,987,654,321.

It also works for smaller numbers: 111 × 111 = 12321.

**5. Zero is the only number** that can’t be represented in Roman numerals.

**6. 10! seconds is exactly 6 weeks.**

**7. 555 is used by some in Thailand**as slang for “hahaha”, because the word for “five” is pronounced “ha”.