Rounding Numbers

≈ 15 min

Rounding replaces a number with a nearby, tidier one — handy for quick estimates. To round to a given place, look at the digit immediately to its right:

if that digit is $5$ or more, round up;
if it is $4$ or less, round down (keep the digit the same).

Everything to the right then becomes $0$ .

Worked example. Round $638$ to the nearest $100$ .

The hundreds digit is $6$ . Look one place to the right — the tens digit is $3$ . Since $3 < 5$ , round down: keep the $6$ and zero the rest. $638 \approx 600$ .

What is $47$ rounded to the nearest $10$ ?

$40$

$50$

$47$

$100$

Round $638$ to the nearest $100$ .

Round $2\,850$ to the nearest $100$ .

Round $4\,500$ to the nearest $1\,000$ .