From the course: Test Prep: GRE
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Mental percents
- [Voiceover] I call this video mental percents because before I get into sort of math teacher percents, I want you to be able to do some percent work in your head. It's just useful, makes your life a little bit easier on the GRE. So let's say we have a number. Let's say we've got a number 67.42. So you should know that 100% of that number is 67.42, that's 100%. So 100% is the whole thing, kind of makes sense. 10%, if we wanted to take 10% of any number, all we have to do is take the decimal point where it is and move it one spot to the left. So if we rewrite it, it's gonna be 6.742, easy way to take 10%. All we did is we took the decimal point and it went from here to here. What about 1%? Same thing, we just move the decimal point again. So 1% is gonna be .6742, really easy way to take 1% of the number, just move the decimal point one, two spots to the left. And we can even get to .1%. We don't often see that in real life, .1% but it's kinda the same thing. We just move it one more…
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Contents
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(Locked)
Integers: Factors, multiples, and remainders2m 7s
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Integers: Even and odd and primes3m 29s
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Order of operations2m
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Number properties3m 46s
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Adding and subtracting fractions3m 36s
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Multiplying and dividing fractions1m 22s
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Decimals3m 9s
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Mental percents2m 55s
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Taking percents and increasing by percents1m 55s
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Percent change3m 36s
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Ratios and proportions4m 20s
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Direct proportion and inverse variation3m 6s
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Exponents2m 7s
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More exponents2m 7s
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Fake exponent rules2m 10s
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Scientific notation3m 32s
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Square roots3m 45s
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Cube and fourth roots2m 34s
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