Mathematics
⏱ ~3-min readAceMark Guide
What this topic is really about
The area of a rectangle is calculated by multiplying its length by its width, which gives 15 cm multiplied by 8 cm, resulting in 120 square centimeters. Distractors like 110 square centimeters represent arithmetic errors in multiplication, while formulas for perimeter or simple addition will not yield the correct 2D space measurement.
The train's speed is first calculated in meters per second by dividing the distance of 200 meters by 10 seconds, yielding 20 m/s. Multiplying this by 18/5 converts it to the correct speed of 72 km/h. Distractors like 54 km/h result from using incorrect conversion factors or calculation errors during the unit conversion.
See the mechanism
According to the BODMAS rule, multiplication must be performed before addition and subtraction. A diagram for this topic isn't available yet — the worked example below walks the same reasoning step by step.
An exam-style question, fully explained
8 + 12 × 2 − 5 =
- Identify what the question tests: 8 + 12 × 2 − 5 =.
- According to the BODMAS rule, multiplication must be performed before addition and subtraction.
- Thus, we first multiply 12 by 2 to get 24, then add 8 and subtract 5 to get the correct answer of 27.
- Simply performing operations from left to right without applying this order of operations would yield an incorrect result.
Traps the examiner sets
- Simply performing operations from left to right without applying this order of operations would yield an incorrect result.
- Distractors like 54 km/h result from using incorrect conversion factors or calculation errors during the unit conversion.
- Rote learning of tables is incorrect because it prioritizes memorization over conceptual understanding, which can hinder a child's long-term mathematical reasoning.
Test your recall
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