Solving measurement word problems
In this chapter we measure length, mass and volume of liquid. A word problem hides the numbers inside a story. Use four simple steps.
Key idea
Understand what is asked, plan the operation (+, −, × or ÷), solve it, then check the answer and the unit.
Watch the units
Change to the same unit before you calculate: 1 m = 100 cm, 1 kg = 1 000 g, 1 ℓ = 1 000 mℓ.
Worked example
A wire is 2 m long. Raju cuts off 65 cm for a frame. How long is the wire left?
Understand: find the length left. Plan: subtract, same unit. Solve: 2 m = 200 cm, then 200 − 65 = 135 cm. Check: 135 + 65 = 200 cm. Answer: 135 cm.
Remember
- Make the units the same first.
- Total or altogether means add; left or remaining means subtract.
- Always write the unit in your answer.