Start by identifying the question. Sketch the situation or write an equation. Include units in your answer, then check whether it makes sense.
Try one together
A class has 6 boxes with 8 pencils in each. It gives away 11 pencils. How many remain?
First find the total: 6 × 8 = 48. Then subtract: 48 − 11 = 37 pencils. Giving pencils away should make the total smaller.
Practice
- A library puts 72 books equally on 8 shelves. How many books are on each shelf?
- Mina has $20. She buys 3 notebooks at $4 each. How much money remains?
- A ribbon is 150 cm long. You cut off 35 cm and then 45 cm. How much is left?
- A club plants 4 rows of 7 seedlings and 3 rows of 6 seedlings. How many seedlings are there?
- A lesson starts at 9:20 a.m. and lasts 45 minutes. When does it finish?
- A rectangular garden is 8 m long and 5 m wide. What is its perimeter?
Show answers and reasoning
- 9 books: 72 ÷ 8 = 9.
- $8: 20 − (3 × 4) = 8.
- 70 cm: 150 − 35 − 45 = 70.
- 46 seedlings: (4 × 7) + (3 × 6) = 28 + 18.
- 10:05 a.m.: 40 minutes takes you to 10:00, then add 5 minutes.
- 26 m: 8 + 5 + 8 + 5 = 26.
Make it your own
Change the numbers in one problem. Solve your version and explain how you checked it. Ask a partner to write a different story that uses the same calculation.