A unit rate is the cost (or amount) for exactly one. If 3 pens cost $6, then one pen costs $6 ÷ 3 = $2. Finding 'how much for one' is always a sharing question, so it is a division: total cost divided by the number of items. The answer for one item is smaller than the total, so if your answer is bigger than the total you have multiplied by mistake. Once you know the cost of one, you can find the cost of any number by multiplying back up.
Explore this idea with maths tools
Maths you can move
Build 8 + 5
Tap two gold counters to fill the ten-frame.
8 in the frame + 5 waiting. The total stays the same.
Words to know
- unit rate
- the amount for exactly one
- per
- 'for each one', signalling a division
- rate
- how one quantity compares to one of another
Worked examples
3 pens cost $6 — cost of 1 pen?
- 1.Divide: $6 ÷ 3.
- 2.= $2 each.
= 2
5 apples cost $10 — cost of 1 apple?
- 1.Divide: $10 ÷ 5.
- 2.= $2 each.
= 2
4 stickers cost $12 — cost of 1 sticker?
- 1.Divide: $12 ÷ 4.
- 2.= $3 each.
= 3
For parents
Method: Divide the total by the number of items.
What to say: Ask 'shared between them, how much is each?' The answer must be less than the total.
Common mistakes:
- Multiplying instead of dividing (3 pens $6 → $18).
- Giving the total back as the cost of one ($6).