Idea 2of 23Builds onThe price for one is the unit price
Price ÷ how many, not the other way
Which number do you divide by which to get the unit price?
Today you'll discover
- which number goes first
- why the other order gives nonsense
- a quick way to spot the mistake
Think first5 pencils for $3.00
Which division gives the price of one pencil?
Decide first, then press Next. Ask: is one item cheaper than the whole pack?
A pack of 5 pencils with a tag: $3.00. Then a bar cut into 5 equal parts, then $3.00 ÷ 5 = $0.60 with 60 cents in each part, then the check 5 × $0.60 = $3.00. The last step asks about 8 erasers for $4.00.
See the whole ideathe big idea and the key word, in one place
The big idea
For the unit price, divide the price by the number of items: price first.
Compare them$3.00 ÷ 5 = $0.60 is dollars per pencil: the unit price. 5 ÷ 3 is pencils per dollar: a different rate, not a price.
Easy to get wrongMultiplying the price by how many gives the cost of many packs. To go from a pack to one item, divide.
Key word
- rate
- a comparison of two different things, such as dollars and pencils: $3.00 for 5 pencils
Ready to use it?
- Write the division that gives a unit price.
- Spot a unit price worked out the wrong way round.