We write numbers using only ten symbols (called Digits).
Đang xem: Place value là gì
Where we place them is important.
The Ten Digits
The Digits we use today are called “Hindu-Arabic Numerals”:
We can use these on their own to count up to 9:
| 0 | |
| 1 | |
| 2 | |
| 3 | |
| 4 | |
| 5 | |
| 6 | |
| 7 | |
| 8 | |
| 9 | |
| ?? |
But what happens after 9?
Ten Or More …
When we have more than 9 items, we start another column – the “tens” column – and we write down how many “tens” we have, followed by how many “ones” (also called “units”).
So we write:
| 10 |
It says we have 1 Ten and 2 Ones, which makes 12.
This can also be written as 1 × 10 + 2 × 1.
Xem thêm: Cách Đưa My Computer Ra Desktop Win 8, Hiện Biểu Tượng My Computer Trên Windows 8/8
We have to put a Zero in the Ones place or “10” looks like “1”.
A Hundred Or More …
When we have more than 99 items, we start another column – the “hundreds” column. Now we need to show how many Hundreds, Tens and Ones:
That shows we have 1 Hundred, 4 Tens and 3 Ones:
This can also be written as 1 × 100 + 4 × 10 + 3 × 1.
Example: “369” means 3 Hundreds, 6 Tens and 9 Ones
Which is also 3 × 100 + 6 × 10 + 9 × 1
And So On …
Xem thêm: Cit Là Gì ? Tìm Hiểu Chi Tiết Về Thuế Thu Nhập Doanh Nghiệp 7 Vấn Đề Bạn Cần Biết Về Cit
Each time we want to show a bigger number we just add one column to the left and we know it is always 10 times bigger than than the column on its right.
