Solve problems explaining which strategy is most efficient | Maths

Starter quiz

Use an efficient method to find the sum of 14,875 and 3,123
- '17,998' ✓
Use an efficient method to find the sum of 9,308 and 5,245
- '14,553' ✓
Match the expression to the correct difference.
- 750,000 − 45,000
  
  ⇔
  
  705,000 ✓
- 750,000 − 50,000
  
  ⇔
  
  700,000 ✓
- 750,000 − 30,000
  
  ⇔
  
  720,000 ✓
- 750,000 − 75,000
  
  ⇔
  
  675,000 ✓
- 750,000 − 55,000
  
  ⇔
  
  695,000 ✓
Use a number line to calculate 50,000 − 34,995 = ______
- '15,005' ✓
Use the ‘constant difference’ strategy to calculate 15,000 − 2,375 = ______
- '12,625' ✓
Two numbers have a total of 367,200 If one of the numbers is 320,000 what is the other number?
- '47,200' ✓

Match these expressions to the strategy you would use to calculate them.
- 1,359,903 + 45,908
  
  ⇔
  
  column addition ✓
- 1,359,903 + 210,000
  
  ⇔
  
  partitioning ✓
- 90,000 − 29,998
  
  ⇔
  
  number line ✓
- 400,000 − 168,993
  
  ⇔
  
  constant difference then column subtraction ✓
- 2,328,992 − 168,445
  
  ⇔
  
  column subtraction ✓
A charity needs to raise £200,000 and it has already raised £57,306 Which strategy is most efficient to use to calculate how much more money it needs to raise?
- Column addition
- Column subtraction
- Partitioning
- Number line
- Constant difference ✓
A charity raises £246,803 in a fundraising event. It then raises another £1,907,368 Which strategy is most efficient to use to calculate how much money it has raised in total?
- Column addition ✓
- Column subtraction
- Partitioning
- Number line
- Constant difference
Find the missing number in this equation. 508,914 = ______ + 205,730
- '303,184' ✓
Calculate the multi-step equation. Think about the strategy which will be most efficient. 205,677 + 499,998 − 200,000 = ______
- '505,675' ✓
Two numbers have a total of 1,690,768 and a difference of 999,412 What are the two numbers? 345,678 and ______
- '1,345,090' ✓

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We know different strategies for addition and subtraction including mental and written strategies.
Looking at the numbers helps us see which strategy is most efficient.
Missing number problems can be rearranged to identify an efficient strategy to solve the problem.

Children may automatically resort to the use of the formal column algorithms. These are not always the most efficient methods.

What do you notice about the numbers? Is there a mental strategy that you could use?

Subtrahend - The subtrahend is the number to be subtracted. It is the second number in a subtraction.
Efficient - Being efficient means finding a way to solve a problem quickly whilst also maintaining accuracy.