Mensuration & Geometry
Mensuration is the most formula-dependent block in the paper, and that is good news: there is nothing to reason out, only a small table to know cold. The one idea worth understanding rather than memorising is scaling — double a square's side and its area goes up four times, not two.
Don't read this page — work through it. Each block asks you to commit to an answer before it tells you anything.
Start here: what do you already know?
Mensuration — true or false?
6 statements · 12s each
The table to know cold
| Shape | Area | Perimeter / Volume |
|---|---|---|
| Square (side a) | a² | 4a |
| Rectangle (l, b) | l × b | 2(l + b) |
| Triangle (b, h) | ½ b h | sum of sides |
| Circle (r) | πr² | 2πr |
| Cube (a) | 6a² surface | a³ volume |
| Cuboid (l,b,h) | 2(lb+bh+hl) | lbh volume |
| Cylinder (r,h) | 2πr(r+h) | πr²h volume |
Use π = 22/7 when the radius is a multiple of 7, and 3.14 otherwise. Exam setters choose radii like 7, 14 and 21 precisely so 22/7 cancels.
Sort by dimension
Is this a length, an area, or a volume?
0/6πr²h
Which group does it belong to?
Commit to the answer
Compute, then check
1/4What is the area of a square of side 12 cm?
150cm²
Method, in order
Match the shape to its formula
Quick reference
Exam tip: when a question says "the side is increased by 20%, find the change in area", do not compute areas. Area scales by (1.2)² = 1.44, so the area rises by 44%. One step.