Mathematics
Grade 4
15 min
Estimate products: word problems
Estimate products: word problems
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1
Introduction & Learning Objectives
Learning Objectives
Identify the key numbers and question in a multiplication word problem.
Round two- and three-digit numbers to their greatest place value to simplify multiplication.
Use rounded factors to calculate an estimated product.
Determine if an estimated answer is reasonable for a given word problem.
Write a complete sentence to answer a word problem using their estimate.
Differentiate between problems that ask for an exact answer versus an estimated answer.
If a video game has 48 levels and you earn 22 coins on each level, about how many coins would you have in total? 🎮 Let's find a super-fast way to get a close answer!
In this lesson, you will learn how to estimate products to solve word problems. Estimating is a powerful math skill that helps you quickly...
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Key Concepts & Vocabulary
TermDefinitionExample
EstimateAn answer that is close to the exact answer. It is not a random guess, but a thoughtful approximation.To estimate 28 + 51, you could think 30 + 50 = 80. The exact answer is 79.
ProductThe result you get when you multiply two or more numbers together.In 7 × 8 = 56, the number 56 is the product.
FactorThe numbers that are being multiplied together to get a product.In 7 × 8 = 56, the numbers 7 and 8 are the factors.
RoundingChanging a number to a simpler, 'friendlier' number that is close to the original. We usually round to the nearest ten, hundred, or thousand.The number 38 can be rounded to 40. The number 123 can be rounded to 100.
AboutA clue word in a word problem that tells you an estimate is needed, not an exact answer. Other clue words include...
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Core Formulas
The Rounding Rule
Look at the digit to the right of the place you are rounding to. If the digit is 5, 6, 7, 8, or 9, you round up. If the digit is 0, 1, 2, 3, or 4, you keep the rounding digit the same.
Use this rule to change the factors in a word problem into simpler numbers before you multiply. For multi-digit numbers, it's often easiest to round to the greatest place value.
Estimation Formula for Products
Estimated Product \approx Rounded Factor 1 \times Rounded Factor 2
This shows the process for estimating. First, round the factors from the word problem. Then, multiply the new, rounded factors to find your estimated product.
4 more steps in this tutorial
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Challenging
The estimated product for a word problem is 3,500. One of the factors in the problem was rounded to 50. Which of these numbers could have been the other original factor in the problem?
A.62
B.78
C.68
D.54
Challenging
To estimate the product of 48 × 195, Mariah calculated 50 × 200 = 10,000. Is her estimate greater than or less than the exact answer?
A.Greater, because both original factors were rounded up.
B.Less, because both original factors were rounded up.
C.Greater, because one factor was rounded up and one was rounded down.
D.It is impossible to tell without finding the exact answer.
Challenging
The Green Team collected 48 bags of cans, with 33 cans in each bag. The Blue Team collected 59 bags of cans, with 24 cans in each bag. About how many more cans did the Green Team collect than the Blue Team?
A.The teams collected about the same amount.
B.About 100 more cans.
C.About 300 more cans.
D.About 600 more cans.
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