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CCSS 1.OA.8 Worksheets

CCSS 1.OA.8 (Common Core, 1st Grade): "Determine the unknown whole number in an addition or subtraction equation relating to three whole numbers. For example, determine the unknown number that makes the equation true in each of the equations 8 + ? = 11, 5 = ?– 3, 6 + 6 = ?." The worksheets below practice this standard. Each one is a free printable PDF with an answer key, comes in multiple versions, and can also be assigned digitally - no login or account needed.

Operations and Algebraic Thinking Work with addition and subtraction equations. 8Determine the unknown whole number in an addition or subtraction equation relating to three whole numbers. For example, determine the unknown number that makes the equation true in each of the equations 8 + ? = 11, 5 = ?– 3, 6 + 6 = ?.

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CCSS 1.OA.8 Worksheets - Solving Mixed Problems within 20 (+ -) worksheet

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Solving Mixed Problems within 20 (+ -)

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Practice finding a missing number in addition and subtraction equations
Get comfortable seeing the unknown in different spots — at the beginning, middle, or end of an equation

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CCSS 1.OA.8 Worksheets - Finding Missing Addend Drills worksheet

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Finding Missing Addend Drills

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Find the missing number that makes an addition sentence true.
Use what you know about addition facts to solve for an unknown addend quickly.
Read and solve equations with a blank or box in different positions.
Build speed and accuracy with mental math when one part of the sum is missing.

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CCSS 1.OA.8 Worksheets - Find Missing Fact worksheet

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Find Missing Fact

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Find the missing fact in addition and subtraction fact families.
Use a fact family to see how addition and subtraction facts are related.

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CCSS 1.OA.8 Worksheets - Adding To a Specic Value worksheet

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Adding To a Specic Value

Find the missing number that makes an addition sentence equal a target number.
Read and solve horizontal addition equations with a blank or missing addend.
Check your answer by adding the two numbers to see if they match the target.

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CCSS 1.OA.8 Worksheets - Finding Missing Addend (Within 10) worksheet

Load up one problem at a time! Ideal for projectors, tablets and computers.

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Finding Missing Addend (Within 10)

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Find the missing number that makes an addition sentence true.
Use the total (sum) to figure out what addend is missing.
Practice quick addition facts with sums less than 10.

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