PERCENTAGE is a Mathematics topic introduced in Year Six and reinforced in lower-secondary classes. It is fundamental in the study of other Mathematics topics, essential in the study of Science, and used in subjects like Geography, Principles of Accounts, Commerce and Economics.
Understanding percentages is necessary in daily life. School-leavers should have a good grasp of percentages.
Go to any outlet that displays discounts in percentages. It is not uncommon to see customers and even sales personnel struggling with the calculation to get to the discounted prices.
A calculator may be at hand. But, see how they go about using it.
For instance, an item is originally priced at RM250, with a 20 per cent discount offered. The calculator will be used to work out the discount amount (RM250 multiplied by 20 per cent, which makes RM50). Then, the amount is deducted from the original price, which works out to RM200.
With the correct understanding of percentages, one would straightaway use the calculator to work out 80 per cent of the original price (RM250 multiplied by 80 per cent, which makes RM200). Better still, mentally calculate eight multiplied by 250, which makes 2,000. Common sense tells you that the answer should be just 200, making the discounted price RM200.
You do not need higher-order thinking skills to solve the problem, as it requires only a good understanding of percentages and simple mental arithmetic skills.
Another common error is in the calculation and expression of percentages. Usually, there is no problem in figuring out that five out of 100 makes five per cent. But, when it is 25 out of 300, the answer unsuspectingly quoted is 0.083 per cent, when it should be 8.3 per cent.
Here is an example of how percentages could be wrongly calculated. It was reported that 300 of 40,000 university intakes would be subjected to the new Integrated Cumulative Grade Point Average assessment system. It was quoted that this made up 0.0075 per cent of the intakes.
The correct percentage should be 0.75 per cent. To get that, it is necessary to multiply by 100 the result of 300 divided by 40,000.
Only three students make up 0.0075 per cent of 40,000.
We have to be careful. Sometimes, to prop up, strengthen and legitimise our arguments, we resort to quoting numbers, numerals, statistics and probabilities.
But instead of making us sound rational, empirical and “scientific”, we become the laughing stock of those who are knowledgeable in the subject.
Schools should not teach students only how to solve Mathematics problems, but also how to understand and appreciate the subject and its uses.
Liong Kam Chong, Seremban, Negri Sembilan