Estimate products: word problems

Learning Objectives Identify keywords in a word problem that signal the need for estimation. Round simple fractions to the nearest benchmark: 0, 1/2, or 1. Estimate the product of a whole number and a simple fraction by rounding the fraction first. Solve one-step word problems that require estimating a product involving a fraction. Use estimation to determine if an answer to a multiplication problem with fractions is reasonable. Explain in their own words how they used estimation to find an answer. If a recipe for one giant cookie calls for 7/8 of a cup of chocolate chips, about how many cups would you need for 5 giant cookies? 🍪 Let's make a smart guess! In this lesson, we will learn how to solve word problems by estimating products. This means we will find an answer...

TermDefinitionExample EstimateTo make a smart guess that is close to the exact answer. We estimate when we don't need a perfect answer.If a toy costs $9.95, you can estimate it costs about $10. ProductThe answer you get when you multiply two or more numbers together.The product of 4 and 5 is 20 because 4 × 5 = 20. FractionA number that shows a part of a whole.1/2 means one part out of two equal parts, like half of a sandwich. Benchmark FractionsSimple, common fractions that are easy to think about, like 0, 1/2, and 1. We use them to help us estimate.The fraction 9/10 is very close to the benchmark fraction 1. Rounding FractionsChanging a fraction to the nearest benchmark fraction (0, 1/2, or 1) to make it easier to work with.We can round the fraction 2/9 to 1/2 because it's clos...

The Fraction Rounding Rule If a fraction is close to 0, round to 0. If it's close to 1/2, round to 1/2. If it's close to 1, round to 1. Look at the numerator and denominator. If the numerator is very small, round to 0 (like 1/10). If the numerator is about half the denominator, round to 1/2 (like 4/9). If the numerator is almost the same as the denominator, round to 1 (like 7/8). The Estimation Formula Whole Number \times Fraction \approx Whole Number \times Rounded Benchmark Fraction To estimate the product, first round the fraction to 0, 1/2, or 1. Then, multiply the whole number by that simple benchmark fraction. The '≈' symbol means 'is approximately equal to'.