3-digit Numbers
Building Numbers
To build bigger numbers, we group smaller ones together.
- First, we group 10 ones to make 1 ten:
= \(10\) ones = \(1\) ten =
- Next, we group 10 tens to make 1 hundred:
= \(10\) tens = \(1\) hundred =
| Hundreds | Tens | Ones |
| 2 | 4 | 3 |
 |  |  |
Definition Digits
The symbols we use to write numbers are called digits. There are ten digits we use to build every number.
| Word | Digit | Cubes |
| zero | 0 | |
| one | 1 |  |
| two | 2 |  |
| three | 3 |  |
| four | 4 |  |
| five | 5 |  |
| six | 6 |  |
| seven | 7 |  |
| eight | 8 |  |
| nine | 9 |  |
Definition Base 10 system
In the base 10-system, the place of a digit tells us its value. We can show a number in many different ways:
- With digits: $$243$$
- In expanded form: $$\begin{aligned}[t] 2\text{ hundreds }&+& 4\text{ tens }&+& 3\text{ ones }\\ 200 &+&40&+&3 \\ \end{aligned}$$
- With words:
two hundred forty-three - In a place value table:
Hundreds Tens Ones 2 4 3 - With blocks:
- with digits: $$243$$
- in expanded form: $$\begin{aligned}[t] 2\text{ hundreds }&+& 4\text{ tens }&+& 3\text{ ones }\\ 200 &+&40&+&3 \\ \end{aligned}$$
- with words:
two hundred forty-three - in a table:
Hundreds Tens Ones 2 4 3 - with cubes:
Zero is a special digit. It acts as a placeholder to show that a place is empty. For example, in the number 20, the zero shows there are no ones.
On the Number Line
- A number line shows numbers in order, like a long ruler. The numbers get bigger as we move to the right.
- To count big numbers faster, we can take big jumps of 10! This is called counting by tens. We say: "ten, twenty, thirty..."
Definition Number Line
A number line is a line that shows numbers in order from smallest to largest. The distance between each number is always the same.