Percent
4aCuZ אחוז
FINDING PERCENTS OF A NUMBER
To find 10% of any number, all you have to do is move the decimal point of that number over one place to the left.
What is 10% of 30?
10% of 30 = 3
So how much is 20% of 30? That's easy. It's twice as much as 10 percent, or 6.
What is 20% of 520?
10% of 520 = 52, so 20% of 520 = 104
To find 1 percent of any number, all you have to do is move the decimal point of that number over two places to the left.
1% of 4 = 0.04
1% of 520 = 5.2
In just the same way we found 20 percent by doubling 10 percent, we can now find 2 percent by doubling 1 percent.
What is 2% of 500?
1% of 500 = 5, so 2% of 500 = 2 × 5 = 10
Now, here's the really great part. We can combine these two techniques to find any percentage test writers can invent.
Let's find 23% of 600
Well, 10% of 600 = 60
So 20% of 600 = 2 × 60 = 120
And 1% of 600 = 6, so 3% of 600 = 18
So what is 23% of 600?
20% of 600 = 120
3% of 600 =18
120 + 18 = 138
CONVERTING PERCENTS TO DECIMALS
the short way to convert from a percentage to a decimal is by removing the percentage sign and moving the decimal point 2 places to the left.
Note: A percentage is just a fraction whose denominator is always 100.
No comments:
Post a Comment