Page 52 - Mathematics

(b) If the digit to the right of a rounding digit is greater than 5, then 1 is added
to the rounding digit and other digits to the right are dropped.

Example 3.9

Round off 0.97381 to 3 decimal places.

Solution
The digit in the third decimal place is 3 and the nearest digit to the right is 8
which is greater than 5. In this case, 1 is added to the rounding digit and each
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digit to the right is dropped. Therefore, 0.97381 ≈ 0.974 to 3 decimal places.

(c) If the digit to the right of a rounding digit is 5, then the rounding digit is
considered as follows:
(i) Add 1 to the rounding digit if it is odd.

(ii) Add 1 to the rounding digit (whether even or odd) if there are other
digits that follow 5 which are all not zero.
(iii) The digit remains unchanged if all the digits following 5 are zeros
and the rounding digit is even.

Example 3.10

Round off the following numbers.
(i) 6.2358 to two decimal places.
(ii) 3.4655 to two decimal places.
(iii) 0.2475 to three decimal places.

Solution
(i) 6.2358 rounded off to two decimal places is 6.24 since the rounding
digit is odd and the digit to the right of the rounding digit is 5.
Mathematics Form One (iii) 0.2475 is rounded off as 2.248 to three decimal places since the rounding
(ii) 3.4655 is rounded off as 3.47 to two decimal places since the rounding
digit is followed by 5 and the digit after 5 are not all zero.

digit is odd.

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Mathematics form 1.indd 46
Mathematics form 1.indd 46 25/10/2024 09:51:13