Rounding: decimal places and significant figures

The Maths Habit

Each number is too long for a headline. What would you write?

A phone costs£849.99About £850
A match is watched by62 850 peopleAbout 63 000 people
A hair is0.0817 mm thickAbout 0.08 mm

Decimal place
The position of a digit after the decimal point.
Significant figure
A digit that tells you the size of a number. Start counting at the first digit that is not zero.

Which end is the number closer to?

5.165.175.1635.16
3.23.33.283.3

Round 2.847 to
2 decimal places.

O2t8h4th7285

7 is 5 or more, so round up

Answer 2.85

Round 6.319 to
1 decimal place.

O6t3h1th963

1 is less than 5, so the 3 stays

Answer 6.3

Round 2.847 to
2 decimal places.

O2t8h4th7285

7 is 5 or more, so round up

Answer 2.85

Round 0.4583 to
3 decimal places.

O0t4h5th8tth30458

3 is less than 5, so the 8 stays

Answer 0.458

Round 2.847 to
2 decimal places.

O2t8h4th7285

7 is 5 or more, so round up

Answer 2.85

Round 7.598 to
2 decimal places.

O7t5h9th8760

8 is 5 or more, so round up

Answer 7.60

Questions 1 to 4

Rounding: decimal places and significant figures worksheet, questions 1 to 4

Which digit is the first significant figure?

40964
0.03813
0.5075

Round 7453 to
2 significant figures.

Th7H4T5O37500

5 is 5 or more, so round up

Answer 7500

Round 0.02864 to
2 significant figures.

O0t0h2th8tth6hth40029

6 is 5 or more, so round up

Answer 0.029

Round 7453 to
2 significant figures.

Th7H4T5O37500

5 is 5 or more, so round up

Answer 7500

Round 61.37 to
1 significant figure.

T6O1t3h760

1 is less than 5, so the 6 stays

Answer 60

Round 7453 to
2 significant figures.

Th7H4T5O37500

5 is 5 or more, so round up

Answer 7500

Round 30 492 to
2 significant figures.

TTh3Th0H4T9O230000

4 is less than 5, so the 0 stays

Answer 30 000

Round 0.03862 to 2 significant figures

A0.04
B0.038
C0.039
D0.0386
A: rounded to 2 decimal placesB: cut off the digits without roundingC: rightD: kept 3 significant figures

Questions 5 to 8

Rounding: decimal places and significant figures worksheet, questions 5 to 8

Further practice

Rounding: decimal places and significant figures worksheet, further practice

Answer sheet

  1. A number is 2.60 when it is rounded to 2 decimal places. What is the smallest it could have been?

    2.595

  2. Round 0.9996 to 3 decimal places and to 2 significant figures.

    1.000 and 1.0

  3. Write a number that is 0.07 to 2 decimal places and 0.066 to 2 significant figures.

    From 0.0655 up to 0.0665

  1. Round 6.4372 to 2 decimal places.

    6.44

  2. Round 73 850 to 2 significant figures.

    74 000

  3. Round 0.05083 to 2 significant figures.

    0.051
Exit tickets to print