This is a level 5 number activity from the Figure It Out series. It relates to Stage 8 of the Number Framework.
solve money problems involving multiplication and division
This activity is appropriate for students at the advanced multiplicative stage of the Number Framework and will give them a lot of practice using mental strategies for all the four operations in a familiar context. The students will need to understand place value across the decimal point. For example, in question 4, which requires $15.00 ÷ 1.70, the students should recognise that the answer must be less than 10. The students also need to recognise that the digits on either side of the decimal point are connected and that the digits to the right of the point are not whole numbers. In question 6, for example, 5 x $1.70 is not $5.35!
All the questions in this activity can be calculated using part–whole mental strategies, such as tidy numbers and doubling and halving. The students could work independently and check their own work with a calculator or use the think, pair, and share strategy (see the notes for pages 2–3) where they work independently and then check their solutions with a classmate. Each pair of students needs to explain and justify their strategies to each other, then find a solution that is acceptable to both. In case they are both right or both wrong, they should share their joint solution with another pair as a check. Most mistakes are likely to occur from missing a particular item or quantity from the list rather than from incorrect mental strategies.
You could easily extend this activity by having the students think of their own questions about orders at the Fine Seafood Restaurant.
Answers to Activity
1. a. $47.10
4. She could buy 8 scoops for $13.60, and she would get $1.40 change.
9. Answers will vary. Two possible answers are:
• 1 fillet with chips ($4.50), 1 sausage ($1.70), 1 dim sim (70c), 1 crabstick (60c), and 1 hamburger ($2.50)
• 2 fish cakes ($3.00), 1 hot dog ($1.70), 1 spicy wedges ($3.00), 1 waffle dog ($1.80), and 1 tomato sauce (50c)