Cathy from the café is trying to calculate her daily sales, but she needs your help subtracting 2 digits from 3 digits.
More resources for Autumn Block 2 Step 12.
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Discussion points for teachers
1. Fill in the missing numbers.
Discuss how you will record each step. Re-cap and model how to exchange. Discuss completing both steps before you fill in the missing numbers.
Buns = 309, Chocolate bars = 419, Biscuits = 97
2. Add the correct inequality symbols to compare the cake sales.
Discuss the inequality symbols and their meaning. How will you know which symbol to use for each? Discuss what you need to do first before filling in the missing symbol.
187 > 169, 277 = 277, 54 < 63
3. What mistake has Cathy made?
Discuss working systematically through the calculation to spot the mistakes. How will you show or record the mistakes. How could you show the correct calculation? Explain the mistakes she made.
241 – 63 = 178. Cathy forgot she needed to exchange because subtraction is not commutative.
4. How many bags has she got left?
Discuss what information we need and where we can get this information from. How will you record your working out?
324 – 68 = 256, 256 – 75 = 181. She has 181 bags left.
5. How many scones could be left?
Discuss which numbers we could start with? What numbers could we subtract and why? Which calculations can we not do and why? Discuss how many different possibilities there are. This question is open-ended for the children to explore.
Various answers, for example: 211 – 62 = 149
Optional discussion points:
What other items might Cathy sell and how might she calculate the sales?
National Curriculum Objectives
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