๐งช Science ๐ข Maths and numbers
The decimal system
๐ In short
The decimal system is a way of writing numbers with only ten symbols, from 0 to 9. A digit's value changes with its place, and each column is worth ten times the one to its right. Perhaps we count in tens because we have ten fingers!
๐คฉ Did you know?
- Any number can be written with only ten symbols.
- Each column is worth ten times the one to its right.
- The extra symbols were dropped from the Indian number system about 1400 years ago.
- Computers use another system with only two symbols, 0 and 1.
๐ Find out more
๐ Place columns
In the number 435, the 5 is in the ones place, the 3 is in the tens place, so it's 30, and the 4 is in the hundreds place, so it's 400. The number equals 400 + 30 + 5.
๐ The job of zero
Zero is very important in the decimal system because it holds an empty place. The number 205 is very different from 25, and the whole difference is the zero in the tens place!
๐ก The decimal point
We use the decimal point to write parts of one: in the number 43.5 there are four tens, three ones and five tenths, that is forty-three and a half.
๐ฏ In our lives
We use the decimal system for money, since a riyal or dirham has a hundred parts, and for measurements: a meter has a hundred centimeters and a kilogram a thousand grams.
๐ธ More pictures
๐งฉ Test yourself
1 In the number 435, what is the 3 worth?
2 How many symbols are there in the decimal system?
3 We use the decimal point to write parts of one: in the number ?? .
4 Which picture shows โThe decimal systemโ?