Complete the addition, subtraction, multiplication, or division sentence

Learning Objectives Identify the missing number in an addition sentence. Find the unknown value in a subtraction sentence. Determine the missing factor in a multiplication sentence. Solve for the missing dividend or divisor in a division sentence. Use inverse operations (fact families) to solve for an unknown number. Check their answer by substituting it back into the original sentence to verify its correctness. If a farmer has some sheep and buys 8 more to have a total of 20, how many did she start with? 🐑 Let's become math detectives and find the missing number! In this lesson, we will learn how to find the missing number in any math sentence, whether it's addition, subtraction, multiplication, or division. This important skill helps us solve puzzles, understan...

TermDefinitionExample Number SentenceA math problem written with numbers, an operation sign (+, -, ×, ÷), and an equals sign (=).6 + 3 = 9 is a number sentence. UnknownThe missing number in a number sentence. It is often shown as a blank line (__), a box (☐), or a question mark (?).In 12 - ☐ = 5, the box represents the unknown number. OperationThe action in a math problem. The four basic operations are addition, subtraction, multiplication, and division.In 4 × 5 = 20, the operation is multiplication. Inverse OperationsOpposite operations that 'undo' each other. Addition and subtraction are inverses. Multiplication and division are inverses.To solve 15 - ☐ = 10, you can use addition to think 10 + 5 = 15. The missing number is 5. Fact FamilyA group of related math facts that use t...

Inverse Rule for Addition and Subtraction If a + ☐ = c, then c - a = ☐. If c - ☐ = a, then c - a = ☐. To find a missing part in an addition or subtraction problem, you can often use the opposite operation with the numbers you already know. Inverse Rule for Multiplication and Division If a × ☐ = c, then c ÷ a = ☐. If c ÷ ☐ = a, then c ÷ a = ☐. To find a missing factor or divisor in a multiplication or division problem, you can use the opposite operation.