One of the math topics which is actually the easiest, but a pet peeve of many students, is percentages.
Let's see if we can simplify it.
The word percentage literally means out of one hundred. (per century) So, all we do in this is try and see how many parts of 100 are involved in the game.
Assume we have an apple. We cut it into two equal halves. One part would be half of the whole. This is equal to 50 portions out of 100. (as 50 is half of 100). So one part out of two works out to be 50 per century or 50 %
We may do our calculations like this
out of 2 - 1
out of 100 - ?
? = (100 x 1)/2 = 50
Similarly, if we had 40 students in the class and 10 of them were boys, then 10 out of 40 is 1/4th. We know that 25 is 1/4th of 100. So 10 out of 40 is the equivalent of 25 %
Remembering reciprocals is a good way to do percentages. Reciprocals are nothing but 1/x where x is any natural number. For instance the reciprocal of 2, i.e. 1/2 = 50%
Reciprocal of 4 (double of 2) = 1/4 = 25% (half the reciprocal of 2)
Reciprocal of 8 (double of 4) = 1/8 = 12.5% (half the reciprocal of 4)
Calculating percentages of numbers is a very simple process, as long as we are good at doubling or halving numbers.
For instance, to calculate 37% of 500, we can split it as 10 + 10 + 10 + 5 + 2
10 % of any number is easy. 10% of 500 is 50
5% is half of 10% = 25
and 2% = twice 1% Now, 1% = 5 so 2% = 10
So we get 37% = 50+50+50+25+10=185
Of course, calculating it by formula 500x37/100 is also ok. Use whichever method is faster and more convenient.
Let's see if we can simplify it.
The word percentage literally means out of one hundred. (per century) So, all we do in this is try and see how many parts of 100 are involved in the game.
Assume we have an apple. We cut it into two equal halves. One part would be half of the whole. This is equal to 50 portions out of 100. (as 50 is half of 100). So one part out of two works out to be 50 per century or 50 %
We may do our calculations like this
out of 2 - 1
out of 100 - ?
? = (100 x 1)/2 = 50
Similarly, if we had 40 students in the class and 10 of them were boys, then 10 out of 40 is 1/4th. We know that 25 is 1/4th of 100. So 10 out of 40 is the equivalent of 25 %
Remembering reciprocals is a good way to do percentages. Reciprocals are nothing but 1/x where x is any natural number. For instance the reciprocal of 2, i.e. 1/2 = 50%
Reciprocal of 4 (double of 2) = 1/4 = 25% (half the reciprocal of 2)
Reciprocal of 8 (double of 4) = 1/8 = 12.5% (half the reciprocal of 4)
Calculating percentages of numbers is a very simple process, as long as we are good at doubling or halving numbers.
For instance, to calculate 37% of 500, we can split it as 10 + 10 + 10 + 5 + 2
10 % of any number is easy. 10% of 500 is 50
5% is half of 10% = 25
and 2% = twice 1% Now, 1% = 5 so 2% = 10
So we get 37% = 50+50+50+25+10=185
Of course, calculating it by formula 500x37/100 is also ok. Use whichever method is faster and more convenient.
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