Ages 7–9🧮 Mathematics10 verified questions on this shelf

Estimating by rounding

Estimate the answer to a calculation and use inverse operations to check answers; apply to increasingly large numbers using rounding and inverse reasoning

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Question 1 of 3

Liam has 158 baseball cards. After trading some with his friends, he now has 93 cards left. How many cards did he trade away? First, estimate the answer by rounding each number to the nearest ten, then find the exact answer and check it by adding the two numbers you get.

Question 2 of 3

Jenna has 462 crayons. After sharing some with her friend, she has 317 crayons left. Before finding the exact number she gave away, she rounds each amount to the nearest ten and then subtracts. What is her best estimate of how many crayons she gave away?

Question 3 of 3

Jasper collected shells. He found 63 shells on the beach and later picked up 19 more. To quickly guess the total, he rounds each number to the nearest ten and then adds. What is Jasper’s estimated total?

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Skill names and descriptions include the Marble Skill Taxonomy © Generative Spark, Inc. (withmarble.com), licensed under ODbL 1.0 (database) and CC BY-SA 4.0 (content). Practice questions are GlowGrades's own, each checked by independent verifiers that must agree before a child ever sees it.