Word Problems: Add & Subtract Within 20 — Answer Key
Part A: Solve the Word Problems
Read each problem. Use the box to show your work. Write the answer.
1. Ms. Clark has 9 pencils on her desk. She gives 5 to students. How many pencils does she have left?
Answer: 4 pencils
Subtract the pencils given away: 9 - 5 = 4 pencils left.
2. Jake sees 6 ducks on the pond. Then 7 more ducks swim over. How many ducks are on the pond now?
Answer: 13 ducks
Add both groups of ducks: 6 + 7 = 13 ducks in all.
3. There are 15 books on the shelf. A student takes 8 books. How many books are still on the shelf?
Answer: 7 books
Subtract the books returned: 15 - 8 = 7 books left.
Part B: Choose the Operation
Write 'add' or 'subtract' to tell what you would do to solve each problem.
1. Tom has 12 grapes. He eats 4. To find how many are left, you subtract.
The phrase 'how many left' after taking away means subtraction: 12 - 4 = 8.
2. Ana has 6 flowers. She picks 8 more. To find the total, you add.
Finding the total means combining groups, which is addition: 6 + 8 = 14.
3. There are 11 cars. Then 3 drive away. To find how many are left, you subtract.
The phrase 'how many left' after driving away means subtraction: 11 - 3 = 8.
4. Rosa has 5 stickers. Kai gives her 9 more. To find the total, you add.
Finding the total means combining groups, which is addition: 5 + 9 = 14.
5. A dog has 13 treats. He eats 7. To find how many are left, you subtract.
The phrase 'how many left' after giving away means subtraction: 13 - 7 = 6.