Rounding decimals is essential for working with money, measurements, percentages, and scientific data. Whether you need to round to 1, 2, 3, or more decimal places, the process is always the same!
12.3456
No matter how many decimal places you're rounding to, follow these same 4 steps:
Identify which decimal place you're rounding to (1st, 2nd, 3rd, etc.)
This digit tells you whether to round up or down.
If that digit is 5 or more → Round UP
If that digit is less than 5 → Round DOWN
Remove all digits after your rounding place.
Example: Round 3.456 to 1 decimal place
→ Keep the 1st decimal: 3.4_
→ Look at the 2nd decimal: 5
→ Since 5 ≥ 5, round UP
Answer: 3.5
Example: Round 12.3456 to 2 decimal places
→ Keep the first 2 decimals: 12.34_
→ Look at the 3rd decimal: 5
→ Since 5 ≥ 5, round UP
Answer: 12.35
Example: Round 3.14159 to 3 decimal places
→ Keep the first 3 decimals: 3.141_
→ Look at the 4th decimal: 5
→ Since 5 ≥ 5, round UP
Answer: 3.142
Example: Round 2.718281828 to 4 decimal places
→ Keep the first 4 decimals: 2.7182_
→ Look at the 5th decimal: 8
→ Since 8 ≥ 5, round UP
Answer: 2.7183
| Number | Round To | Check Digit | Answer |
|---|---|---|---|
| 5.678 | 1 decimal | 7 (2nd decimal) | 5.7 |
| 0.12345 | 2 decimals | 3 (3rd decimal) | 0.12 |
| 99.9999 | 1 decimal | 9 (2nd decimal) | 100.0 |
| 7.8901 | 3 decimals | 1 (4th decimal) | 7.890 |
| 3.14159 | 2 decimals | 1 (3rd decimal) | 3.14 |
Wrong: 3.456 → 3.46 → 3.5 (rounded twice!)
Correct: 3.456 → Look at 2nd decimal (5) → 3.5 (round once!)
Wrong: Round 7.89 to 1 decimal by looking at the 9
Correct: Look ONE place to the right of where you're rounding (the 8 in this case)
Wrong: 12.3456 rounded to 2 decimals = 12.346
Correct: 12.3456 rounded to 2 decimals = 12.35 (drop the 6)
Look at the digit AFTER where you're rounding
5, 6, 7, 8, 9 → UP ⬆️
0, 1, 2, 3, 4 → DOWN ⬇️
✓ Round ONCE, not twice
✓ Look ONE digit right
✓ Drop all extras