Three ribbons have lengths 4.6 m, 4.57 m and 4.605 m. Arrange the lengths from the longest to the shortest.
- 4.605, 4.6, 4.57
- 4.605, 4.57, 4.6
- 4.57, 4.6, 4.605
- 4.6, 4.605, 4.57
Need a hint?
Write every number with the same number of decimal places, then compare digit by digit from the left, using place value.
Worked answer
- Write each length with three decimal places: 4.600, 4.570, 4.605.
- The ones are all 4.
- Tenths: 4.600 and 4.605 have 6 tenths; 4.570 has 5 tenths, so 4.57 is the shortest.
- 4.600 and 4.605 have the same hundredths (0). Thousandths: 5 is more than 0, so 4.605 is longer than 4.6.
- From the longest to the shortest: 4.605, 4.6, 4.57.
Answer: 4.605, 4.6, 4.57 m
The mistake this question tests
Habit
Calculation slip
Pupils often compare the digits after the decimal point as whole numbers, so 4.57 looks bigger than 4.6 because 57 is bigger than 6.
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