What is Rounding?
In everyday life, we rarely need exact numbers. A doctor might say a patient weighs 59 kg, not 58.7 kg. A news report might say 3 million people attended an event, not 2,947,813. This process of replacing a number with a simpler, nearby value is called rounding.
Replacing a number with a nearby value that is simpler or easier to work with, while staying as close as possible to the original value.
When we round, we use the symbol ≈, which means approximately equal to.
Think of rounding like choosing the nearest bus stop. If you're standing between two stops, you walk to whichever one is closer. Rounding works exactly the same way — you go to the nearest "stop" (place value) on the number line.
Rounding Whole Numbers to the Nearest 10
To round a whole number to the nearest 10, we find which multiple of 10 it is closest to.
Imagine a number line from 40 to 50:
- 41, 42, 43, 44 are all closer to 40 → round down to 40
- 46, 47, 48, 49 are all closer to 50 → round up to 50
- 45 is exactly halfway → we always round up
The Golden Rule for Rounding:
To round to a particular place value, look at the digit one place to the right of it.
- If that digit is 0, 1, 2, 3, or 4 → round down (keep the digit the same)
- If that digit is 5, 6, 7, 8, or 9 → round up (increase the digit by 1)
Round to the nearest 10:
a) 63 → Look at the units digit: 3 → it's less than 5 → round down → 60
b) 475 → Look at the units digit: 5 → round up → 480
c) 3029 → Look at the units digit: 9 → round up → 3030
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