Decimal places (d.p.) refer to the digits

to right of the decimal point. For

example ‘23.845’ have 3 decimal places.

The numbers we get from a computation

often contains worthless digits that must

be thrown away.

Whenever we do this we must round our

answer to the required decimal places.

Rule 1

If the first digit to be discarded is greater

than 5, or a 5 followed by a non zero in

any of the decimal placed to the right,

then round up by the last digit retained.

Number Rounded to Three

Decimal Places

4.3654 4.365

4.3656 4.366

4.365501 4.366

1.764999 1.765

1.927499 1.927

Rule 2

If the first digit to be discarded is less

than 5, round down by the last digit

retained.

Write -6.0439 to 2 d.p. Here 3 is first

discarded digit and 4 is the last retained

digit. Since 3<5 so we round down and

hence result will be -6.04.

Rule 3 (Important)

If the first digit to be discarded is equal

to 5, always round to the nearest even

number.

Numbers Rounded to 2 d.p.

4.365 4.36

4.355 4.36

7.76500 7.76

7.75500 7.76

Do not Forget to…

When you were asked to write a number

to for example to 3 d.p., consider the

first 4 d.p. places during the computation

and write the end result to 3 decimal

places.

For example, here is a series of

addition and result is required

to 2.d.p

85.18851.18911.294.15

94.15945.15375.857.7

57.7572.7894.3678.3

86.18858.18911.2375.8894.3678.3

Any

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