Subtraction facts

Subtraction facts

Pencil and paper
Overview
Connecting to the Curriculum
Marking Student Responses
Working with Students
Further Resources
This task is about using an algorithm to calculate subtraction problems.
Write your answers in the boxes.
You can use the remaining area to do your working.
 

1

  17

-   9

equals area

2.

  74

- 21

equals area

3.

  52

- 37

equals area

4.

  775

- 432

equals area

5.

  536

- 277

equals area

6.

  400

- 126

equals area

7.

  7146

- 5438

equals area
    
Level:
4
Curriculum info: 
Maths, Number and Algebra, Number Strategies
Keywords: 
nemp, subtraction
Description of task: 
For this NEMP task students calculate the answers to a series of subtraction problems.
Answers/responses: 
   

Y8 (09/1997)

1.

8

87%

2.

53

94%

3.

15

80%

4.

343

92%

5.

259
NOTE: Wrong answer of 341.

70%
6%

6.

274
NOTE: Wrong answer of 326.

59%
7%

7.

1 708
NOTE: Wrong answer of 2 312.

65%
6%
Diagnostic and formative information: 
Commentary
On the questions which did not involve re-naming (carrying), about 90 percent of year 8 students were successful. When re-naming was required, success rates dropped substantially for year 8 students. It is noteworthy that the 447 year 8 students produced 60 different answers to question 7.