Painting a room

surface area calculation

Walls are 2(L+W)×H − doors/windows. A 4×3×3 m room needs 42 − 4 = 38 m². At 12 m²/L, you need ~3.2 L paint.

Buying carpet

floor area

Living room 5×4 m needs 20 m² carpet. Add 5–10% wastage for trimming → buy 22 m². Mensuration sells flooring.

Filling a tank

volume

A cylindrical tank radius 1 m, height 2 m holds π·1²·2 ≈ 6,283 L. Every water-tank label uses cylinder volume.

Wrapping gifts

surface area

A box 30×20×10 cm needs roughly 2(LW + LH + WH) = 2,200 cm² wrapping paper. Add overlap and there's your gift-wrap budget.

Construction estimates

brick counts, paint litres

Concrete for a 10 m × 6 m × 0.15 m slab = 9 m³. At ₹6,000/m³, that's ₹54,000 of concrete alone.

Land valuation

plot area

A trapezoid plot 30 m and 25 m parallel sides, 40 m apart → area = ½(30+25)(40) = 1,100 m². Per-square-foot pricing flows from this.