Word Problems with Change Unknown - Up to 20
ā The mysterious middle number! Sometimes you know the start, and you know the end... but you don't know what happened in between!
Concept
These word problems are like puzzles where the middle piece is missing. šÆ **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.