Okay in this video I want to talk about some arithmetic basics, and what we're gonna talk
about is finding the percent
a number. So a lot of times, you know, that's
usually how I see it stated. They'll say
maybe, for example what is 75 percent
of the number six, and I'm gonna talk about a procedure here in just a second
but just a couple remarks here
umm, 100%
of a number is the same number, so if somebody says, you know what's a 100%
of 10? Well 100% of 10 is the number 10.
Umm, if you're finding if you wanna know a percentage
when the percentage is less than a 100%, umm,
so if we take a percentage less than a 100 of a number that's going to
make the numbers
smaller that we get out. So 75%
of the number six I know that's going to be a number smaller than six
If we find a percentage where the percentage is bigger than
100% of a number
that's going to make the number larger. Just like 100%
doesn't change the value of the number. If you find 200%
of a number it's gonna double it, and if you find
if you find 300% of a number that's simply gonna triplet it.
Umm, et cetera.
....So here's kind of the
procedure, you know, if I have to find the percentage of a number.
So what I basically do whatever
wherever I see the percentage sign I replace that percentage with a decimal,
and then I need to move the decimal two places to the left and
remember what this does. This just simply converts from a
percentage to a decimal. That's the way you do it, and then I just take this
decimal form and I multiply it
umm, by the number that I'm trying to find the percentage
of. Umm, if you've forgotten how to do
arithmetic multiplying numbers involving decimals,
I'm gonna pull a post, a video response. It'll be somewhere
you know, right beneath the video where you can check that out,
and umm, if you if you've forgotten a little bit of the decimal
multiplication. So again we wanted to find 75%
Whoops, I'm already jumping ahead. Seventy-five percent
of the number six. So
again all I do is I take my number
75 and I replace
the percentage sign. Notice the percentage sign simply gets turned into
a decimal, but now we have to move that decimal place
umm, two places to the left. So I'm gonna
turn my 75% into the equivalent decimal form
of .75, and then it says umm,
we want .75 of the number six.
All we do is we multiply, think about the word
"of" as being multiplication. So it says we have to take
.75 and simply multiply it by six.
Okay, so when I do my, umm,
arithmetic, I like to put the larger number on top. So there's my .75
multiplied by six,
so six times five is thirty, so I'll drop down the zero
carry the three, six times seven is forty-two.
42 plus 3 is 45, and remember now we count
the number of decimal places. So the first one
it was, we had two decimal places. The number at the bottom has no decimal places
so our final answer, we go over two spots and then that's where we put our decimal.
So 75% of the number 6
would be the number 4.5. Okay.
and again certainly that is a little bit smaller than six.
Let's maybe do at least one more. let's do
a, you know, maybe let's get a larger percentage. so
maybe let's do one that's a little, maybe a little longer.
Let's find, umm, how about 225%... of
I don't know. How about the number 24. Just making 'em up here.
Okay, so one thing intuitively I do you usually at this point as well
is remember we said if you, if you
multiply if you find 200% of a number it doubles it.
Well, if we were to double 24, 24 times 2 is 48.
So that's if I, if I had found 200%
of the number 24. Likewise if I were to find 300%
of the number 24, I would have to triple it, and you can check that if you
multiply 24 by 3 you get 72.
So I know, okay, well 200% of the number gets me 48,
300% gives me 72. What i'm saying is intuitively I
know that
225% of that number
should be something a little bit larger than 48. It's gonna certainly be closer to 48
than it is to 72. So umm, again I probably went through that arithmetic a
little bit quick but
umm, the idea is your estimating. You're just doing a quick estimation just to make
sure that you're in the ballpark.
Same procedure though. Okay so my 225,
I replace the percentage with a decimal
then I have to move it over two spots, so 2.25. Again, umm,
"of" think about that as being multiplication. I put my number here in
parentheses for no particular reason.
Umm, so pay no mind to my parentheses.
Again, umm, I like to put the larger number,
well, I should say the number with more digits on top.
So, I'm gonna put my 2.25 on top,
and then it says I have to simply multiply that by 24.
We're gonna do the same thing we're just gonna multiply like normal, and then count up
our decimal places. So 4 times 5 is 20.
I'll drop down my zero, carry the two. Four times two is eight.
plus two is ten, so I'll drop down my zero,
carry the one. Four times two is eight, plus one will give me nine.
Some people make a zero. Again I make a little "x,"
and then I simply multiply. Two times five which is zero.
I would have to carry the one. So 2 times 2 is 4, plus 1 is 5.
And then, umm, 2 times 2 would be 4.
So now I add up my numbers. I'll get zero, zero
four and five, and again now have to do the same thing. I simply
count the number decimals that I saw in my original
problem when I was multiplying. Notice the first number has two decimal places
So, it has, umm, the numbers shifted, two decimal places to the left.
I don't see, I see zero decimals showing up in my second one.
So again we take our final answer and we move our decimal place
two points to the left, which would give us the number 54.
Umm, and again this is the way I like to go through this at the very beginning.
Umm, you know, maybe I got confused about where the decimal place goes. Is it, is it 5.4 is it 540?
Well again if you remember intuitively that 200%
is roughly twice this number which would be 48.
Umm, you know, the only place where it would really make sense to put the decimal would be after the four.
Okay, so it says 225, umm, 225% of the number 24 is simply equal to the number 54.
Alright, umm, I hope this video makes
makes a little bit of sense. If you have any comments or questions, as always, feel
free to post them.
Umm, and, like I said I'm gonna post a video response, so if you need to see some more
examples about the
multiplication involving decimals certainly feel free to check that out too.