Lesson 2: Rounding

Property

How to round a whole number to a specific place value:

1. Locate the given place value.
2. Underline the digit to the right of the given place value.
3. Determine if this digit is greater than or equal to 5.
   • Yes: add 1 to the digit in the given place value. Handle any regrouping (like 9 becoming 10).
   • No: do not change the digit in the given place value.
4. Replace all digits to the right of the given place value with zeros.

Examples

• To round $4,862$ to the nearest hundred, look at the tens digit (6). Since $6 \ge 5$, round up the hundreds digit. The result is $4,900$.
• Rounding $12,345$ to the nearest thousand means looking at the hundreds digit (3). Since $3 < 5$, the thousands digit stays the same. The result is $12,000$.
• Rounding $49,850$ to the nearest thousand involves looking at the hundreds digit (8). Since $8 \ge 5$, we add 1 to the 9, which requires regrouping. The result is $50,000$.

Explanation

Rounding simplifies a number. Look at the digit just to the right of the place you're rounding to. If that digit is 5 or more, you round up. If it's 4 or less, you keep the digit the same.

Property

To round a decimal to the nearest integer, find the closest whole number. Since $1 = 10^0$, rounding to the nearest integer means rounding to the nearest multiple of 1.

Examples