Rukasha Maths

GCSE maths Beta

Signed numbers and order of operations · Revision guide

Foundation · Number · 1 page in the PDF

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Learning objectives

  • Calculate with positive and negative numbers.
  • Apply the agreed order of operations.

Key ideas

Numbers further right on a number line are greater.

Subtracting a negative means adding its positive opposite.

a−(−b)=a+ba-(-b)=a+b

For multiplication and division: matching signs give positive; different signs give negative.

Calculate brackets, then powers, then multiplication and division, then addition and subtraction.

At the same priority, work from left to right.

Worked examples

Example 1

Calculate the expression in the correct order.

Calculate the bracket first.

−6+3×(8−5)=−6+3×3-6+3\times(8-5)=-6+3\times3

Multiply before adding.

−6+9=3-6+9=3
33

Example 2

Subtract a negative number.

−7−(−4)=−7+4=−3-7-(-4)=-7+4=-3
−3-3

Watch out

Do not calculate every expression from left to right. Operation priority comes first.