Foundation and Higher · rounding

Rounding.
Draw the line,
check next door.

decimal places and
significant figures

every rounding question —

Cut, then look

draw a line where you want to cut

the digit after it decides

step 1 of 4

Decimal places

1. Two digits after the point, then a line.

2. Look at the next digit: 6. Round up.

✓ 5 or more rounds up. 4 or less stays

3.4762 to 2 d.p.

3.4762

3.48 6 is 5 or more: round up

step 2 of 4

Significant figures

1. Count from the first non-zero digit.

2. 6 rounds the 7 up to 8.

✓ 48 000, not 48: keep it the same size

47 620 to 2 s.f.

47620

48 000 keep the size: fill with zeros

step 3 of 4

Small numbers

1. Leading zeros are not significant.

2. The first significant figure is the 4.

✓ 0.0048

0.004762 to 2 s.f.

0.004762 front zeros do not count

0.0048

step 4 of 4

The 9 trap

1. Rounding the 9 up carries into the 2.

2. Keep the zero: it shows 1 decimal place.

✓ 3.0, not 3 or 2.10

2.97 to 1 d.p.

2.97

3.0 not 3

rounding —

d.p.

count from the decimal point

s.f.

count from the first non-zero digit

Next digit

5 or more: round up

The rounded number should be
about the same size as the original.

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