Page 49 - Mathematics

(b) If the digit to the right of a rounding digit is 5, then the rounding digit is treated
in three main ways.
(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 Tanzania Institute of Education
the rounding digit is even.

Example 3.5

Round off each of the following numbers according to the given instructions.
(a) 2.635 to the nearest hundredths.
(b) 42,243,568 to the nearest thousands.
(c) 8,115,684 to the nearest ten thousands.

Solution
(a) 2.635 rounded off to the nearest hundredths is 2.64 since the rounding

digit is odd and the digit to its immediate right is 5.
(b) 42,243,568 rounded off to the nearest thousands is 42,244,000 since digits
after 5 (which is on the right of 3 as a rounding digit) are all not zero.

(c) 8,115,684 rounded to the nearest ten thousands is 8,120,000 since digits
after 5 (which is on the right of 1 as a rounding digit) are all not zero.

Example 3.6

Round off:.
(a) 6.645 to the nearest hundredths.
(b) 8,125,000 to the nearest ten thousands.

Solution
Mathematics Form One
(a) 6.645 rounded off to the nearest hundredths is 6.64 since digits after 5
are all zeros.
(b) 8,125,000 rounded off to the nearest ten thousands is 8,120,000 since all
the digits after 5 are all zero.

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