Page 56 - Mathematics

6. When zero is written at the end of an approximated number, including decimals,
it is a significant figure. For example, 2.73 ≈ 3.0, and in this case, 0 is a
significant figure. Also, 45,961 ≈ 46,000, the zero at the third-place value is
a significant figure.
7. All the zeros that are on the right of the non-zero digit are significant if they
come from measurements. For instance, 20 m has two significant figures and
300 g has 3 significant figures.

Note:
(i) Significant figures are also known as significant digits.
(ii) Significant figures are always counted from left towards the right of a
number.
Tanzania Institute of Education

Rounding off numbers by significant figures
Rounding off numbers to a specified number of significant figures is one of the
methods of approximations. Similar rules for rounding off numbers are used in
writing numbers to a given number of significant figures.

Example 3.14

Determine the number of significant figures in each of the following numbers.
(a) 2.3004 (c) 0.00002 (e) 0.00165000
(b) 0.0804 (d) 4,002,000,000 (f) 3,000 km

Solution
(a) 2.3004 has 5 significant figures.
(b) 0.0804 has 3 significant figures.
(c) 0.00002 has 1 significant figure.
(d) 4,002,000,000 has 4 significant figures.
(e) 0.00165000 has 6 significant figures.
(f) 3,000 km has 4 significant figures.

Example 3.15
Mathematics Form One Solution

Write 38,176 correct to 1 significant figure.

Counting from left to right, the given number has 5 significant figures. The
first digit, 3 is increased by one to become 4 (since 8 is greater than 5), and
each of the right-side digits become zero. Thus, 38,176 ≈ 40,000 correct to
1 significant figure.

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25/10/2024 09:51:14
Mathematics form 1.indd 50
Mathematics form 1.indd 50 25/10/2024 09:51:14