Estimate products of multi-digit whole numbers and decimals by rounding factors to appropriate place values or selecting compatible numbers that are easy to multiply. The estimate preserves the product’s scale and provides a benchmark for judging whether an exact calculation is reasonable; it is not expected to reproduce the exact product, and the precision chosen should reflect the context.
To estimate a product, replace each factor with a nearby number that is easier to multiply. Choose rounding that keeps the answer’s size reasonable.
Example: Estimate .
Round each factor to a friendly number:
Multiply the rounded numbers:
So,
The symbol means “approximately equal to.” The estimated product is about 1,000. This gives you a quick benchmark: an exact answer should be close to 1,000, not 100 or 10,000.
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