Introduction to Percentages
When you are saying "percentages" you are really saying PER 100. All percentages go over, or fall within 100.
(Click on this link for a quick introductory video)
(Click on this link for a quick introductory video)
Therefore... When we see 25 out of 100 grids filled in, this means 25 per 100 or 25%. ALSO written as 25/100.
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And... when we see 50 out of 100 grids filled in, this means 50 per 100 or 50%. ALSO written as 50/100.
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100% means "ALL" or 100/100
50% means half, or 50/100
5% means 5/100ths
Using Percent
Because "Percent" means "per 100" we think, DIVIDE by 100.
So 75% really means 75/100
And 100% is 100/100, or exactly 1 (100% of any number is just the number, unchanged)
And 200% is 200/100, or exactly 2 (200% of any number is twice the number)
Because "Percent" means "per 100" we think, DIVIDE by 100.
So 75% really means 75/100
And 100% is 100/100, or exactly 1 (100% of any number is just the number, unchanged)
And 200% is 200/100, or exactly 2 (200% of any number is twice the number)
Let us look at some examples:
Example: Calculate 25% of 80
25% means 25/100
(25/100) × 80 = 20
So 25% of 80 is 20
Example: 15% of 200 apples were bad. How many apples were bad?
15% means 15/100
(15/100) × 200 = 15 × 2 = 30 apples
30 apples were bad
or
15/100 = ?/200
(in this case, you will "cross-multiply and divide". 15 = ? )
100 200
"Cross-multiply" means 15 x 200 =3000
Then you divide 3000/100 = 30
Therefore, the formula can be reduced to is = %
of 100
Example: if only 10 of the 200 apples were bad, what percent is that?
Let us solve this one using the formula above, is = %
of 100
"10 apples OF 200 is % over 100"
10= IS while 200=OF, where we aim to find the percent of the whole, 100.
10 = %
200 100
"Cross-multiply" 10 x 100= 1000
and
Divide 1000/200 = 5
Therefore, 5 of the apples are bad.
Example: Calculate 25% of 80
25% means 25/100
(25/100) × 80 = 20
So 25% of 80 is 20
Example: 15% of 200 apples were bad. How many apples were bad?
15% means 15/100
(15/100) × 200 = 15 × 2 = 30 apples
30 apples were bad
or
15/100 = ?/200
(in this case, you will "cross-multiply and divide". 15 = ? )
100 200
"Cross-multiply" means 15 x 200 =3000
Then you divide 3000/100 = 30
Therefore, the formula can be reduced to is = %
of 100
Example: if only 10 of the 200 apples were bad, what percent is that?
Let us solve this one using the formula above, is = %
of 100
"10 apples OF 200 is % over 100"
10= IS while 200=OF, where we aim to find the percent of the whole, 100.
10 = %
200 100
"Cross-multiply" 10 x 100= 1000
and
Divide 1000/200 = 5
Therefore, 5 of the apples are bad.