JSS2 First Term Mathematics Lesson Note – Approximation

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WEEK 3

APPROXIMATION

CONTENT

• Approximation of numbers: Decimal places, Significant figures
• Quantitative Reasoning

Approximation of numbers

To approximate a number means to write a number near the original number that is a number not exactly the original number. It may be a bit more or less than the original. Whole numbers can be approximated to the nearest ten, hundred, thousand, million, etc.

Let’s consider the table below:

NUMBER	APPROXIMATED
186	190 to the nearest ten
1586	1600 to the nearest hundred
346	300 to the nearest hundred
1481	1480 to the nearest ten
687.4	687 to the nearest unit
4225	4000 to the nearest thousand
69685.42	69690 to the nearest ten
2.634	2.630 to the nearest thousandth
0.214	0.214 to the nearest thousandth

From the above table, we can see that when numbers are approximated, they do not give the exact result expected. In approximation, we only consider the next figure we are approximating. If it is up to 5 and above, we take it as one (1) and add the (1) to the figure we are approximating to. If it is less than 5, we make it zero (0) and add zero to the figure.

Examples:

1. Sum 48, 226 and 592 and approximate your answer to the nearest hundred.

Solution:

48 + 226 +592 = 866.

To the nearest hundred 866 = 900

2. Simply 1984

Solution:                                    

To the nearest hundred = 700

3. The heights of three educators are 1.45m, 3m and 2.11m. Calculate the total height and approximate to the nearest hundredth.

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