Tripp and Tori are visiting the Olympic games. They buy a selection of merchandise and need help working out the cost of individual items using inverse operations.
More resources for Autumn Block 3 Step 7.
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Discussion points for teachers
1. If 108 people are leaving the block, how many rows of seats are there?
Discuss possible calculations and their inverses to find and check the correct answer.
108 ÷ 12 = 9 rows
2. What could they have purchased?
Discuss which strategies can be used to ensure that exactly 40 tokens are spent. Discuss different options depending on whether all items are the same or if there is a combination of different items.
Various answers, for example: 40 ÷ 10 = 4 so they could have purchased 4 paninis
3. If T-shirts cost 10 tokens each and one postcard costs half the price of a T-shirt or less, how many postcards could Tripp have bought?
Discuss the first step in this problem to identify the remaining tokens. Discuss strategies to work methodically to ensure all possibilities are found. This question is open-ended for the children to explore.
50 – 20 = 30 tokens remaining. Postcards could cost 5 tokens (30 ÷ 5 = 6); 3 tokens (30 ÷ 3 = 10); 2 tokens (30 ÷ 2 = 15) or 1 token (30 ÷ 1 = 30), so Tripp could have bought 6, 10, 15 or 30 postcards.
4. How much does one postcard cost?
Discuss which calculations can be done to find the correct answer.
50 – 17 = 33 tokens remaining. Each postcard costs 3 tokens because 33 ÷ 11 = 3.
5. How much does one keyring cost?
Identify the inverse operation to calculate the correct answer.
36 ÷ 4 = 9 tokens
6. How many posters did Tori buy?
Discuss the possible strategies to find the missing value using the information provided and drawing upon known facts.
Find the missing value for the programmes: 7 x 11 = 77. Use that information to calculate the missing total: 185 – 77 – 36 = 72. Use the inverse to find the final answer: 72 ÷ 6 = 12. Tori bought 12 posters.
National Curriculum Objectives
Mathematics Year 5: (5C6a) Multiply and divide numbers mentally drawing upon known facts
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