Maths · Rung 23 of 30

Units and estimation

Changing units means multiplying or dividing by 10, 100 or 1,000: 1 km is 1,000 m and 1 m is 100 cm. Hours are different: an hour is 60 minutes. Before calculating, estimate the order of magnitude; if a door comes out at 20 m, something is wrong.

Where this sits

Comes after
Decimals

Exercises from this rung

Generated by the app, from easiest to hardest

  1. How long is an adult's stride?

    • 75 cm
    • 75 m
    • 7,5 cm
    • 7,5 m

    Why About 75 cm. The other options are ten, a hundred or a thousand times off: the error of a misplaced unit.

    easier

  2. How much does an apple weigh?

    • 15 g
    • 15 kg
    • 1,5 kg
    • 150 g

    Why About 150 g. The other options are ten, a hundred or a thousand times off: the error of a misplaced unit.

    in between

  3. Round 6119 to the nearest hundred.

    Answer 6100

    Why The deciding digit is 1: under 5, so stay at 6100.

    harder