Worked examples
Two examples
Example 1
Estimate by rounding each number to the nearest hundred first: 487 + 312
- 487 rounds to 500, and 312 rounds to 300.
- 500 + 300.
Answer: 800
Example 2
Estimate by rounding each number to the nearest ten first: 48 × 21
- 48 rounds to 50, and 21 rounds to 20.
- 50 × 20.
Answer: 1,000
Where this is taught: Quiz 2: Comparing, Ordering, and Rounding, “Estimation: rounding with a purpose”
The drill
Ten problems
This drill also has challenge problems. They use the same skill, set up the way the GED test sometimes sets up a problem, so that it looks new at first.
How many:
Type each answer, then press Check my answers at the bottom. Commas in large numbers are fine.Write each answer on the line. The answer key, with the reasoning, is on the last page.