| Places | Tens | Ones | Tenths | Hundredths | Thousandths | Ten Thousandths | Hundred Thousandths | |
|---|---|---|---|---|---|---|---|---|
| Number | 2 | 1 | . | 7 | 8 | 9 | 3 | 4 |
| Rounded Number | 2 | 1 | . | 7 | 8 | 9 |
- 9 is in the thousandths place and 3 is in the ten thousandths place
- Since the digit in the ten thousandths place (3) is less than 5, the digit in the thousandths place (9) does not change
- The digits to the right of the thousandths place are dropped
- 21.78934 rounded to the nearest thousandth (three decimal places) = 21.789
