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Common Core Math3rd GradeOperations & Algebraic Thinking

3.OA.4: Find the Unknown Number in an Equation

Also written as 3.OA.A.4 and CCSS.MATH.CONTENT.3.OA.A.4 · Cluster: Represent and solve problems involving multiplication and division.

Make a 3.OA.4 WorksheetAll 25 3rd Grade Math Standards

The Official Wording

Determine the unknown whole number in a multiplication or division equation relating three whole numbers. For example, determine the unknown number that makes the equation true in each of the equations 8 × ? = 48, 5 = _ ÷ 3, 6 × 6 = ?

Common Core State Standards, Grade 3, Operations & Algebraic Thinking · Read it at the source · Checked October 14, 2026

What 3.OA.4 Means in Plain English

Third graders find the missing number wherever it sits: 8 × ? = 48, ? ÷ 4 = 9, or 7 = ? ÷ 4. They turn each one into a question, like “8 times what makes 48?”, and answer it with a fact they know.

The equal sign has to mean “is the same as,” or 7 = ? ÷ 4 looks broken. In 4th grade students write letters for unknowns in multistep word problems (4.OA.3), and in 6th grade they solve equations like 8x = 48 (6.EE.7).

3.OA.4 I Can Statements

  • I can find the missing factor in 8 × ? = 48.
  • I can find a missing number on either side of the equal sign.
  • I can check my answer by putting it back into the equation.

3.OA.4 Worked Example

The hardest form first: the unknown is the number being divided, and it sits on the right of the equal sign.

Problem

Find the number that makes the equation true: 7 = n ÷ 4.

Solving 7 = n ÷ 4
  1. Read it aloud: 7 is the same as some number divided by 4. The equal sign means both sides are worth the same.7 = n ÷ 4
  2. Turn it into a story: some pencils are shared by 4 students, and each student gets 7. How many pencils were there?n pencils ÷ 4 students = 7 each
  3. Four students with 7 pencils each is 4 groups of 7. That is multiplication.4 × 7 = n
  4. Count four sevens: 7, 14, 21, 28.n = 28
Answern = 28

Check it: Put 28 back in: 28 ÷ 4 = 7, so 7 = 28 ÷ 4 is true.

Common Mistakes with 3.OA.4

Doing the operation that is showing

8 × ? = 48 answered 384, because 8 × 48 = 384

Try this: Have students read it as a question, “8 times what makes 48?”, and count by eights until they reach 48.

Reading the equal sign as “the answer is”

7 = ? ÷ 4 left blank with “it’s backwards” written beside it

Try this: Swap the two sides and read it aloud as “same as”: what number divided by 4 is the same as 7?

Dividing the two numbers in sight

? ÷ 6 = 3 answered 2, because 6 ÷ 3 = 2

Try this: Turn the equation into a sharing story: some cookies shared by 6 people gives 3 each, so how many cookies were there?

Where 3.OA.4 Fits

Comes Before1.OA.8Find the unknown in an addition or subtraction equation, like 8 + ? = 11.2.OA.1Solve addition and subtraction word problems with the unknown in any position.
Alongside3.OA.3Solve multiplication and division word problems with a symbol for the unknown.3.OA.6Find 32 ÷ 8 by asking what times 8 makes 32.
Comes Next4.OA.3Solve multistep word problems with a letter for the unknown quantity.6.EE.7Solve equations like x + 7 = 15 and 8x = 48.

Practice 3.OA.4

Math Worksheet GeneratorFree ToolMissing-number facts with the blank in every position, 8 × ? = 48, ? ÷ 4 = 9 and 7 = ? ÷ 4, plus an answer key.Missing numbersFacts to 100Answer key
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Quick Check

  1. 8 × ? = 48
  2. ? ÷ 5 = 9
  3. 4 = 36 ÷ ?

3.OA.4: Other Names

3.OA.43.OA.A.4CCSS.MATH.CONTENT.3.OA.A.4

Common Core State Standards © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved. Official wording from the Common Core State Standards PDFs at corestandards.org, last checked October 14, 2026. The explanation, I can statements, example, mistakes and practice on this page are EMStudio’s own, written beside the official wording. They are not part of the standard.