Zero: the amazing number
📖 In short
Zero means “nothing”, and yet it's one of the most important inventions in the history of math! Thanks to it we can tell 5, 50 and 500 apart, and without it computers and phones wouldn't work. The Arabic word “sifr” has a long story: the word “zero” comes from it.
🤩 Did you know?
- Computers write everything, pictures, sounds and games, with just the two digits 0 and 1.
- Water freezes at 0 degrees Celsius.
- The ancient Romans had no symbol for zero at all.
- Adding one zero to the right of a number makes it 10 times bigger: 7, then 70, then 700.
🔎 Find out more
🌟 Zero, the place keeper
When we write 205, the zero tells us: “there are no tens here”. If we took it away, the number would become 25, a completely different number. That's why we call zero a “place keeper”.
🔍 Where did zero come from?
Indian scholars drew zero as a dot or a small circle and called it “shunya”, meaning empty. The Arabs translated it as “sifr”, also meaning empty, al-Khwarizmi spread it in his books, and then Europeans took it up: it became “zephirum” and then “zero”.
💡 Calculating with zero
Adding zero to a number doesn't change it: 7 + 0 = 7. And multiplying any number by zero gives zero: 7 × 0 = 0, because we took seven zero times! Dividing by zero isn't allowed in math.
🎯 Zero in our lives
We find zero in the temperature at which water freezes, on a new car's mileage counter, and in the countdown before a rocket launches: 3, 2, 1, 0… liftoff!
🧮 Worked examples
- 8 + 0 = 8Zero doesn't change a number when adding.
- 8 × 0 = 0Eight times nothing is nothing.
- 4 × 10 = 40When we multiply by 10 we add a zero to the right of the number.
📚 Key words
- Zero
- The number that means nothing, written 0
- Place keeper
- Zero when it holds the place of an empty position in a number, like in 105
- Countdown
- Counting from big to small until we reach zero
🧪 Try it at home
Write the digits 3, 0 and 5 on three small pieces of paper. How many different numbers can you make by arranging them? (like 305, 530…). What happens when zero comes first?
🧩 Test yourself
1 What is 9 × 0?
2 What does the zero mean in the number 407?
3 Which word does the word “zero” come from?