Find Value of Digit
Introduction
When you have a large number, such as 7,854, it can be tricky to remember what the value of each digit is. For example, the 8 in 7,854 represents 800. To work out the value of a digit is important because if you need to subtract or add two numbers, you need to match up the values of the digits.
If you make a number table, you can 'sort' your number, making it easier to work out what the value of the digit is.
Terms
Lesson
The first thing to do to find the value of a digit is to enter the entire number into a number table. These are ways of ordering a number so that you can easily match a digit to a column. For example:
| Hundred-Thousands | Ten-Thousands | Thousands | Hundreds | Tens | Ones |
|---|---|---|---|---|---|
If we get a number like 18,475, we can plug that into a number table. An important thing to remember is that we plug it in from the right, starting with the ones column. We want to make sure that there are no gaps on the right-hand side of the table. Plugging in 18,475 gives us:
| Hundred-Thousands | Ten-Thousands | Thousands | Hundreds | Tens | Ones |
|---|---|---|---|---|---|
| 1 | 8 | 4 | 7 | 5 |
To find the value of a particular digit, we need to multiply the digit by the value of the column. For example, to find the value of the Hundreds column we find the digit in the column and multiply by 100. For the thousands column, we multiply the digit by 1,000 and so on.
So, in 18,475, if we want the value of the tens digit, we would look at the table and see that the tens column has 7 in it. Since it's the tens column, we multiply 7 by 10, giving us 70.
If we are working with decimals, we need to add in extra columns to the right. We would then multiply the value of the digit in this column by the column value, such as 0.1 for tenths and 0.01 for hundredths.