Topics
3. Subtraction
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United States of AmericaUT
Grade 3

3.03 Estimation first

Lesson
Practice
Lesson

Are you ready?

Do you remember how to estimate the answer to an addition problem?

Choose the right answer.

  1. $143+33$143+33 will be in the:

    $100$100s

    A

    $200$200s

    B

Learn

Let's see how we can estimate the answer to a subtraction problem, by rounding our numbers first.

Apply

Choose the right answer.

  1. $38-6$38−6 will be in the:

    $30$30s

    A

    $20$20s

    B

Remember!

When we need to solve a subtraction problem, we can still round our numbers to the nearest $10$10 or $100$100, just as we would for addition. We don't need the exact answer so this gives us an idea of what our answer should be close to.

Outcomes

3.OA.8

Solve two-step word problems.

3.OA.8.a

Solve two-step word problems using the four operations. Know how to perform operations in the conventional order when there are no parentheses to specify a particular order (Order of Operations). (Limit to problems posed with whole numbers and having whole number answers.)

3.OA.8.b

Represent two-step problems using equations with a letter standing for the unknown quantity. Create accurate equations to match word problems.

3.OA.8.c

Assess the reasonableness of answers using mental computation and estimation strategies, including rounding.

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