Word Problems with Change Unknown - Up to 20
❓ The mysterious middle number! Sometimes you know the start, and you know the end... but you don't know what happened in between!
Do this: Read the concept below, then try the quiz or activity.
Concept
These word problems are like puzzles where the middle piece is missing.
🎯 The "Change Unknown" Puzzle: Story: "You had 12 cookies. Then your dog ate some. Now you only have 7 cookies left. How many cookies did the dog eat?" * Start: You had 12. * Result (End): You have 7. * Change (Middle): ???
Equation: 12 - ??? = 7 How do we find the mysterious middle number? Use your math tricks! You can use addition to find the missing part! Ask yourself: * "7 plus WHAT equals 12?" * Let's count up from 7... 8, 9, 10, 11, 12! That's 5 steps. * The missing number is 5! The dog ate 5 cookies.
Try it
Crack the case of the missing middle number!
Instructions: Read the story, find the start and end, and figure out the change!
Problem 1: Tom had 15 toy cars. He gave some to his little brother. Now Tom has 9 cars left. How many cars did he give away? * Equation: 15 - ___ = 9 * Start at 9 and count up to 15! * Answer: He gave away ___ cars.
Problem 2: There were 8 birds on a wire. More birds flew in. Now there are 14 birds. How many birds flew in? * Equation: 8 + ___ = 14 * Answer: ___ birds flew in.
Problem 3: You have 20 dollars. You buy a toy. Now you have 11 dollars left. How much did the toy cost? * Answer: The toy cost ___ dollars.