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Formula for percentageThe formula for percentage is the following and it should be easy to use:  We will take examples to illustrate.Let us start with the formula on the left An important thing to remember: Cross multiply It means to multiply the numerator of one fraction by the denominator of the other fraction Examples #1: 25 % of 200 is____ In this problem, of = 200, is = ?, and % = 25 We get: is/200 = 25/100 Since is in an unknown, you can replace it by y to make the problem more familiar y/200 = 25/100 Cross multiply to get y × 100 = 200 × 25 y × 100 = 5000 Divide 5000 by 100 to get y Since 5000/100 = 50, y = 50 So, 25 % of 200 is 50 Examples #2: What number is 2% of 50 ? This is just another way of saying 2% of 50 is___ So, set up the proportion as example #1: is/50 = 2/100 Replace is by y and cross multiply to get: y × 100 = 50 × 2 y × 100 = 100 Since 1 × 100 = 100, y = 1 Therefore, 1 is 2 % of 50 Examples #3: 24% of___ is 36 This time, notice that is = 36, but of is missing After you set up the formula, you get: 36/of = 24/100 Replace of by y and cross multiply to get: 36/y = 24/100 y × 24 = 36 × 100 y × 24 = 3600 Divide 3600 by 24 to get y 3600/24 = 150, y = 1500 Therefore, 24 % of 150 is 36 Now, we will take examples to illustrate how to use the formula for percentage on the right Examples #4: To use the other formula that says part and whole, just remember the following: The number after of is always the whole The number after is is always the part If I say 25 % of___ is 60, we know that the whole is missing and part = 60 Your proportion will will like this: 60/whole = 25/100 After cross multiplying, we get: whole × 25 = 60 × 100 whole × 25 = 6000 Divide 6000 by 25 to get whole 6000/25 = 240, so whole = 240 Therefore, 25 % of 240 is 60 Examples #5: ___% of 45 is 9 Here whole = 45 and part = 9, but % is missing We get: 9/45 = %/100 Replacing % by x and cross multiplying gives: 9 × 100 = 45 × x 900 = 45 × x Divide 900 by 45 to get x 900/45 = 20, so x = 20 Here we go!. I hope these formula for percentage were helpful. Still struggling with fractions? Get rid of your fears and frustrations once and for all! Buy my ebook. It offers a thorough coverage of fractions!  
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