New
New
Year 6

Explain how adjusting the minuend can make mental calculation easier

I can explain how adjusting the minuend can make mental calculation easier.

New
New
Year 6

Explain how adjusting the minuend can make mental calculation easier

I can explain how adjusting the minuend can make mental calculation easier.

warning

These resources will be removed by end of Summer Term 2025.

Switch to our new teaching resources now - designed by teachers and leading subject experts, and tested in classrooms.

Lesson details

Key learning points

  1. If you increase the minuend the difference increases by the same amount.
  2. If you decrease the minuend the difference decreases by the same amount.
  3. Partitioning the minuend can simplify the calculation.

Keywords

  • Minuend - The minuend is the number being subtracted from.

  • Subtrahend - A subtrahend is a number subtracted from another.

  • Adjust - When you adjust you make a change to a number. This is done to make a calculation easier to solve mentally.

  • Inverse - The inverse is the opposite or reverse operation. For example, subtraction is the inverse operation of addition.

Common misconception

Pupils may be eager to use columnar written methods for larger integers and decimals instead of considering the values and using an efficient strategy.

Emphasise the importance of trying different mental methods so that pupils aren't reliant on written methods that prevent them from fully grasping the underlying structure of additive problems.

In the second lesson cycle a pictogram is used. Consider when your pupils last interpreted a pictogram; pre-teaching this representation may lead to more success within the lesson.
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

Loading...

6 Questions

Q1.
In the following equation, which number is the difference? 38 − 12 = 26
38
12
Correct answer: 26
Q2.
Solve the following calculation mentally by adjusting the minuend and subtrahend. 157 − 32 =
Correct Answer: 125
Q3.
Solve the following calculation mentally using unitisation. = 290 − 120
Correct Answer: 170
Q4.
Solve the following calculation mentally by adjusting the subtrahend and then the difference. 1,050 − 902 =
Correct Answer: 148
Q5.
Solve the following calculation using a mental strategy. = 211 − 97
Correct Answer: 114
Q6.
7,261,000 − 11,000 =
Correct Answer: 7,250,000

6 Questions

Q1.
Find the missing number in the equation below by adjusting the minuend to match the ones digit of the subtrahend. 153 − 36 =
Correct Answer: 117
Q2.
Find the missing number in the equation below by adjusting the minuend to match the ones digit of the subtrahend = 269 − 46
Correct Answer: 223
Q3.
Find the missing number in the equation below by adjusting the minuend to match the ones digit of the subtrahend. 2,887 − 44 =
Correct Answer: 2,843
Q4.
Find the missing number in the equation below by adjusting the minuend to match the ones digit of the subtrahend. 1,567 − 59 =
Correct Answer: 1,508
Q5.
Find the missing number in the equation below by adjusting the minuend. 3,084 − 0.46 =
Correct Answer: 3083.54
Q6.
Find the missing number in the equation below by adjusting the minuend. = 967,000 − 35,000
Correct Answer: 932,000