Rounding is the process of reducing the number of significant digits in a number while keeping its value close to the original. It's one of the most fundamental mathematical skills used in everyday life, from calculating tips at restaurants to estimating budgets and simplifying complex calculations.
Whether you're rounding to the nearest ten, hundred, or decimal place, the basic principle remains the same: you're making a number simpler while maintaining reasonable accuracy.
Determine which digit place you're rounding to. This is called the "rounding place."
Example: Round 1,234 to the nearest hundred
The hundreds place is the "2" (representing 200)
Examine the digit immediately to the right of your rounding place. This digit determines whether you round up or down.
Example: In 1,234, look at the tens place
The tens digit is "3" (which is less than 5)
If the digit is 5 or more, round UP. If it's less than 5, round DOWN.
Example: Since 3 < 5, we round DOWN
Keep the hundreds digit as "2"
All digits to the right of the rounding place become zero.
Example: 1,234 → 1,200
The "3" and "4" become zeros
Look at the ones digit:
Example: 47 → Look at 7 (ones) → 7 ≥ 5 → Round UP to 50
Example: 32 → Look at 2 (ones) → 2 < 5 → Round DOWN to 30
Look at the tens digit:
Example: 567 → Look at 6 (tens) → 6 ≥ 5 → Round UP to 600
Example: 234 → Look at 3 (tens) → 3 < 5 → Round DOWN to 200
Look at the hundreds digit:
Example: 5,678 → Look at 6 (hundreds) → 6 ≥ 5 → Round UP to 6,000
Example: 1,234 → Look at 2 (hundreds) → 2 < 5 → Round DOWN to 1,000
Same rules apply! Look at the digit to the right of where you're rounding:
To 1 decimal: 3.47 → Look at 7 (hundredths) → 7 ≥ 5 → Round UP to 3.5
To 2 decimals: 12.345 → Look at 5 (thousandths) → 5 rounds UP to 12.35
Wrong: Rounding 234 to nearest hundred by looking at the ones digit (4)
Correct: Look at the tens digit (3) → Round DOWN to 200
Wrong: 1,449 → 1,450 → 1,500 (rounded twice)
Correct: 1,449 → Look at hundreds digit (4) → 1,000 (round once)
Wrong: 567 rounded to nearest hundred = 6
Correct: 567 rounded to nearest hundred = 600
| Number | Round To | Look At | Answer |
|---|---|---|---|
| 78 | Nearest ten | 8 (ones) | 80 |
| 352 | Nearest hundred | 5 (tens) | 400 |
| 4,567 | Nearest thousand | 5 (hundreds) | 5,000 |
| 3.67 | Nearest tenth | 7 (hundredths) | 3.7 |
| 12.345 | 2 decimal places | 5 (thousandths) | 12.35 |
| 999 | Nearest hundred | 9 (tens) | 1,000 |
5 or more? Round UP ⬆️
Less than 5? Round DOWN ⬇️
→ Nearest 10: Check ones
→ Nearest 100: Check tens
→ Nearest 1000: Check hundreds
1. Find rounding place
2. Look right
3. Round up/down
4. Replace with zeros
✓ Only round ONCE
✓ Look ONE digit right
✓ Zero out the rest