A cylindrical drum of internal radius 35 cm holds cooking oil to a depth of 1.2 m. How many litres of oil is that? (Use π = 22/7, and 1000 cubic cm = 1 litre.)

Put every length in centimetres: the depth is 120 cm, so the oil occupies (22/7) $\times 35^{2}x120=3850\times 120=462000$ cubic cm. Dividing by 1000 gives 462 litres. The trap 462000 leaves the answer in cubic cm; 0.462 converts to cubic METRES (divide by 1000000) and then labels the result litres; 4620 divides by only 100.