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How do you order numbers and calculate accurately with the four operations, directed numbers and the correct order of operations?

Order positive and negative integers, decimals and fractions; use the four operations with whole numbers, decimals and directed numbers; and apply the correct order of operations (BIDMAS), including brackets, powers and roots.

A focused answer to the Eduqas GCSE Mathematics number content on the structure of the number system and calculation, covering ordering, the four operations, directed numbers, and the order of operations (BIDMAS).

Generated by Claude Opus 4.811 min answer

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  1. What this dot point is asking
  2. Ordering numbers
  3. The four operations and directed numbers
  4. The order of operations (BIDMAS)
  5. Why this matters

What this dot point is asking

The Eduqas number content opens with the structure of the number system and calculation: ordering integers, decimals and fractions, calculating with the four operations including directed (signed) numbers, and applying the order of operations. This is the bedrock of the whole qualification. Both components test it, and because Component 1 is non-calculator, fluent written and mental arithmetic is essential. A sign slip or an order-of-operations error in the first line of working carries through every later step, so accuracy here protects marks across the entire paper.

Ordering numbers

To order a mixed list of integers, decimals and fractions, put them all in one form first.

For decimals, line up the decimal points and pad with trailing zeros so each has the same number of places: 0.3,0.305,0.350.3, 0.305, 0.35 become 0.300,0.305,0.3500.300, 0.305, 0.350, which order easily. For fractions, rewrite them over a common denominator: 23,34,58\tfrac{2}{3}, \tfrac{3}{4}, \tfrac{5}{8} over 2424 are 1624,1824,1524\tfrac{16}{24}, \tfrac{18}{24}, \tfrac{15}{24}, so the order is 58<23<34\tfrac{5}{8} < \tfrac{2}{3} < \tfrac{3}{4}. With negative numbers, remember the number line: βˆ’7-7 is smaller than βˆ’3-3, because it lies further left.

The four operations and directed numbers

Adding and subtracting directed numbers is where most marks are lost.

So βˆ’4Γ—6=βˆ’24-4 \times 6 = -24 (unlike signs), βˆ’20Γ·(βˆ’5)=4-20 \div (-5) = 4 (like signs), and βˆ’7βˆ’(βˆ’10)=βˆ’7+10=3-7 - (-10) = -7 + 10 = 3. A number line helps with the additions and subtractions: start at the first number and step right for ++ or left for βˆ’-. Distinguishing position (which can be negative) from distance (which cannot) is a recurring exam theme, as in temperature, depth and bank-balance problems.

The order of operations (BIDMAS)

When an expression mixes operations, the order is fixed.

So 5+2Γ—32=5+2Γ—9=5+18=235 + 2 \times 3^2 = 5 + 2 \times 9 = 5 + 18 = 23: the power, then the multiplication, then the addition. Division and multiplication share a level, so 12Γ·2Γ—312 \div 2 \times 3 is worked left to right as 6Γ—3=186 \times 3 = 18, not 12Γ·612 \div 6. Treating a fraction bar as a bracket matters: 8+42+1=123=4\dfrac{8 + 4}{2 + 1} = \dfrac{12}{3} = 4, evaluating top and bottom before dividing.

Why this matters

Calculation underpins every other area of the Eduqas course, from compound measures to probability to solving equations. Because AO1 (using standard techniques) is half of the marks and AO2 and AO3 reward clear reasoning, accurate signed arithmetic and a correct order of operations are constantly assumed rather than re-tested in isolation. Securing them frees attention for the harder reasoning that earns the top grades.

Exam-style practice questions

Practice questions written in the style of WJEC Eduqas exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.

Eduqas 20193 marksWork out βˆ’6+4Γ—(βˆ’3)βˆ’(βˆ’2)-6 + 4 \times (-3) - (-2). (Foundation, Component 1, non-calculator.)
Show worked answer β†’

Apply BIDMAS: multiplication before addition and subtraction.

Multiplication first: 4Γ—(βˆ’3)=βˆ’124 \times (-3) = -12.

Now work left to right: βˆ’6+(βˆ’12)=βˆ’18-6 + (-12) = -18, then βˆ’18βˆ’(βˆ’2)=βˆ’18+2=βˆ’16-18 - (-2) = -18 + 2 = -16.

Markers award a mark for the correct product βˆ’12-12, a mark for handling the double negative βˆ’(βˆ’2)=+2-(-2) = +2, and a mark for the final answer βˆ’16-16. The usual error is to work strictly left to right and add before multiplying.

Eduqas 20214 marksA diver is at βˆ’18-18 m relative to sea level. She descends a further 77 m, then rises 1111 m. Find her final depth, and find the total vertical distance she travels. (Foundation, Component 2, calculator.)
Show worked answer β†’

Track the directed numbers for the final depth, but add absolute distances for the total travelled.

Final depth: βˆ’18βˆ’7+11=βˆ’25+11=βˆ’14-18 - 7 + 11 = -25 + 11 = -14, so she is at βˆ’14-14 m (14 m below sea level).

Total distance travelled: she moves 77 m down then 1111 m up, so 7+11=187 + 11 = 18 m.

Markers give marks for the correct signed arithmetic, the final position βˆ’14-14 m, recognising distance ignores direction, and the total 1818 m. Subtracting to get 7βˆ’117 - 11 for the distance is the common slip; distance is never negative.

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