How do you get revolution of wheel with diameter as 84cm and has covered 3.3km

1 revolution of the wheel = pi * 84 cm = 263.89 cm

There are 100*1000 = 100,000 cm in 1 km so:-

Number of revolutions when travelling 3.3 km = (3.3 * 100,000) / 263.89 = 1250.5 revolutions