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Directed numbers · Ages 12–13

The four operations mixed

Brackets, powers, times and divide, plus and minus; the sign first at each step.

How to do it

Method

Brackets, powers, times and divide, plus and minus; the sign first at each step

(−2) × [3 − (−1)] + 5 = −8 + 5 = −3

Another way

Split the signs

−5 + 8 − 3 + 2 = (8 + 2) − (5 + 3) = 2

In full

The order is the same as for positive numbers: brackets, then powers, then times and divide, then plus and minus. At each step, settle the sign, then the size: (−2) × [3 − (−1)] + 5 = (−2) × 4 + 5 = −8 + 5 = −3. With only plus and minus, you can split the positives from the negatives and then combine: −5 + 8 − 3 + 2 = (8 + 2) − (5 + 3) = 2; going left to right gives the same.

Worked examples

Have a go first, then open each one for the answer and the working.

  1. Example 1

    (−14 + 13)² =

    Show the answer and working

    Answer: 1

    The bracket first: −14 + 13 = −1. Then square: (−1)² = 1.

  2. Example 2

    (+0.9) × (−4) + 0.68 =

    Show the answer and working

    Answer: −2.92

    Multiply first: same signs give a positive, different signs a negative, and the size is 0.9 × 4. Then add 0.68: −2.92.

  3. Example 3

    (−5) × (9 − 18) = 45

    True or false?

    Show the answer and working

    Answer: True

    9 − 18 is negative, and negative times negative is positive. Work it through and compare with 45.

Practice questions to try

Try these 5; the answers are at the end. For a whole worksheet, see VIP worksheets below.

  1. 1.22 + (−8) × 6 =

    Answer:

  2. 2.(−7) + 4 × (−9) =

    Answer:

  3. 3.−22 + 14 − 8 + 14: the positives add to , the negatives to −, so the answer is .

    Fill in each blank

    Answer:

  4. 4.(−8) × (2 − 18) = 130

    True or false?

    Answer:

  5. 5.(−0.9) × (−2) + 0.62 =

    Answer:

All the answers
  1. 1. −26
  2. 2. −43
  3. 3. 28, 30, −2
  4. 4. False
  5. 5. 2.42
Free worksheet: The four operations mixedWorking out, multiple choice and word problems, with answers and working, to print or save as a PDF

VIP practice notes and papers

Aimed at tests and exams: questions on this topic, new every time, to print or save as a PDF.

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