Exponents and Scientific Notation

bobbym · 2011-07-06 04:01:22

What happened? Where are you confused?

zee-f · 2011-07-06 04:03:32

so is 6 correct ? this lesson is hell of confusing

bobbym · 2011-07-06 04:04:24

Yes, I would bet my dough on it.

zee-f · 2011-07-06 04:07:52

i got b for #7

zee-f · 2011-07-06 04:09:03

and for 8 i got c

Bob · 2011-07-06 04:09:42

hi zee-f

F has a lot of zeros. So many that (i) it's tiresome writing them all and (ii) you couldn't even enter it in a calculator like that.

So scientific notation (also known as standard index form) gives a way to show how big a number is without having to put all the zeros.

has the effect of moving the decimal point 21 places.

So start with 6.6 and move the point 21 places.

You get 6600 000 000 000 000 000 000.

That's the same number in 'ordinary' form.

Might be helpful to learn how to show the powers properly so that 1021 looks like

Bob

edit: You start with square brackets, then the word math, then close off the bracket.

Then the expression you want to show. In this case 10^{21} The curly brackets are needed when the 'power' is more than one digit.

Then finish with square bracket, /math, close square bracket.

Hint. If someone has done this sort of thing in a post, click on it, and you'll see how they made the expression. Only the opening and closing math commands will be missing.

Bob

Last edited by Bob (2011-07-06 04:15:02)

bobbym · 2011-07-06 04:09:50

Nope! For 7 I got A.

67 000 000 = 6.7 x 10^7

zee-f · 2011-07-06 04:10:11

no 8 i got b my bad

bobbym · 2011-07-06 04:14:04

B is correct for 8

zee-f · 2011-07-06 04:17:17

and for #9 i got c

bobbym · 2011-07-06 04:18:30

Hi zee-f;

Bob is going help now.

Bob · 2011-07-06 04:20:13

hi zee-f

I've put a diagram below that I use with classes when we are doing this.

You can copy it and print it off.

You want to do (9) ?

9. Divide the following numbers using scientific notation: (4 x 102)/(1 x 103)
A5 x 105
B4 x 101
C4 x 105
D4 x 10-1
E5 x 101
F5 x 10-5

Use the diagram to convert these numbers.

4 x 10^2

Write a four in the hundreds column, fill in with zeros afterwards and you get 400

Write a 1 in the thousands column, fill in with zeros and you've got 1000

So the question is asking

Opps. That's less than one so my diagram is in-complete.

I'll repost with the other half as well.

Bob

Last edited by Bob (2011-07-06 04:25:10)

zee-f · 2011-07-06 04:25:25

so is my 9 correct ?????

Bob · 2011-07-06 04:29:02

no. Don't rush. Let's make sure you understand what you are doing then you'll be able to any problem like this for yourself.

Bob

part two of the diagram below.

Have a good look at both parts.

Then I'll post again.

zee-f · 2011-07-06 04:31:44

dosnt that give me 2/5

anonimnystefy · 2011-07-06 04:33:37

hi zee-f

yes that is correct,but try to get a power of ten in the numerator.

zee-f · 2011-07-06 04:33:56

do 4*10^-1= 2/5

anonimnystefy · 2011-07-06 04:34:37

hi zee-f

that is correct.

zee-f · 2011-07-06 04:34:57

so*

zee-f · 2011-07-06 04:36:17

thanx alot

Bob · 2011-07-06 04:36:50

hi zee-f

The two diagrams OVERLAP at units. If you print them both and cut then them out you'll have two strips; the large numbers are on the left. This strip goes from units, through tens, hundreds all the way up to thousand millions. I had to stop there because I wanted something I could print for my students that would fit on a page.

The second strip starts at units and goes smaller as you go rightwards, down to the fraction 1 over a thousand million (0.000000001). The '1' is in the thousand millionth column.

You can join the strips to make one long strip by overlapping the units column and sticking them together. At the join the columns should go ......... hundreds, tens, units (ONCE!), then tenths, hundredths .........

Does this make sense so far?

edit: While I was typing that I see you've jumped ahead and got the answer. Well done. But you didn't need to go via 2/5.

Go back to 400/1000 = 4/10.

Look at diagram two. Put a '4' in the tenths column and you can see the right power is 10 to the -1. So you get to

So using the diagrams you can get straight to the right answer.

Bob

Last edited by Bob (2011-07-06 04:43:32)

zee-f · 2011-07-06 04:42:11

yup thanx for the help
oooh and for #10 i got d

anonimnystefy · 2011-07-06 04:44:03

hi zee-f

that is incorrect.how did you get that answer?

Bob · 2011-07-06 04:47:24

Oh hang on. I was just checking that. I think d is correct.

But it isn't helping us to help you when you aren't showing the powers properly. It makes it hard to sort out the questions and the possible answers.

Bob

zee-f · 2011-07-06 04:47:40

Perform the following calculation: (1 x 10^2)(2 x 10^3)/(1 x 10^2)
because 1*100=100
2*1000=2000

200000\(1*10^2)

200000\100=2000

Math Is Fun Forum

#26 2011-07-06 04:01:22

Re: Exponents and Scientific Notation

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#28 2011-07-06 04:04:24

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#43 2011-07-06 04:34:37

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#45 2011-07-06 04:36:17

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