## Why Rounding Matters in the Field In the electrical trade, you often deal with: - Digital meter readings - Scaled voltage and resistance values - Precision tolerances for parts and components These values frequently contain long decimals that must be **rounded** to match tools, documentation, or significant figures. Examples: - A digital meter may show **5.6789 A**, but you may need to record it as **5.68 A** - Wire sizes or insulation specs may be rounded for standardization ## Place Values Review Each digit after the decimal point has a name: |Place|Value|Example in 3.786| |---|---|---| |Tenths|1 digit|7| |Hundredths|2 digits|8| |Thousandths|3 digits|6| In **3.786**: - 7 is in the **tenths** place - 8 is in the **hundredths** place - 6 is in the **thousandths** place ## Rounding Rules To round a number to a specific decimal place: 1. Find the digit **at** the place value you’re rounding to. 2. Look at the **next digit to the right**. 3. If that digit is **5 or more**, round **up**. 4. If that digit is **4 or less**, round **down** (leave it as is). 5. Remove all digits after the rounded place. ### Example 1: Round 3.786 to the **nearest hundredth** - Hundredths digit is 8 - Next digit (thousandths) is 6 - Since 6 is greater than 5, round 8 **up** to 9 **Result:** 3.79 ### Example 2: Round 12.443 to the **nearest tenth** - Tenths digit is 4 - Next digit is 4 - Since 4 is less than 5, keep 4 **Result:** 12.4 ### Example 3: Round 0.8467 to the **nearest thousandth** - Thousandths digit is 6 - Next digit is 7 - Round 6 **up** to 7 **Result:** 0.847 ## Real-World Example: Digital Multimeter Reading Your multimeter shows a voltage of **120.578 V**, but the specification only requires reporting to the nearest tenth. - Tenths digit is 5 - Next digit is 7 - Round up **Result:** $120.6$ V This keeps your report clean and compliant with spec sheets and QC logs. ## Try It Yourself 1. Round **4.368** to the nearest **hundredth** 2. Round **9.957** to the nearest **tenth** 3. Round **0.4321** to the nearest **thousandth** ## Summary - Rounding keeps measurements and reports practical and aligned with precision needs - Use the **digit to the right** to determine whether to round up or down - Round to the required place value: tenths, hundredths, thousandths