## Your Questions About Odd Calculator

Richard asks…

## How do you use a slide rule?

Alright, my physics final is next week and the teacher is letting us use slide rules but not calculators… I can’t find a good sight…for stupid people….with pretty pictures, maybe some easy instructions…please help.

ps mostly I just need to know how to square root something and multiply/divide. Also, I can’t watch videos on this computer.

### admin answers:

Those are a few of the simplest things to do on a slide rule, so it shouldn’t be so hard to learn.

Slide rules differ in a lot of the scales they have, but several scales are common to all of them. Mainly, the A, B, C, D, and L scales.

A – on top of frame

B – on top of slide

C – on bottom of slide

D – on bottom of frame

The C and D scales are the „main“ number scales — they each go from 1 to 10. But on all these scales, any trailing 0’s are omitted. So it’s labeled,

1 2 3 4 5 6 7 8 9 1

Each number on it, represents that number, times any ± integer power of 10.

The A and B scales are the „square“ scales — they each go from 1 to 100, in two cycles from 1 to 10. Again, the trailing 0’s are omitted. So it’s labeled,

1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1,

which you can think of as representing

1 2 3 4 5 6 7 8 9 10 20 30 40 50 60 70 80 90 100

It’s important to take note of the distinction between the two cycles of A & B — they’re for even (left cycle) and odd (right cycle) powers of 10. So

0.03, 3, 300, 30,000, are located on the left half;

0.003, 0.3 30, 3000, are located on the right half.

If you line the cursor up on 2 on the D scale, it will sit over the left-cycle 4 on the A scale. If you set it to 5 on the D, it will line up over the right-cycle 2.5 on the A scale, which then represents 25.

So to take the square root of 9, set the cursor to the left-cycle 9 on A, and read the answer on D. (3)

To take the square root of 90, set the cursor to the right-cycle 9 on A, and read the answer on D. (a little less than 9.5)

Taking square roots requires no movement of the slide; just slide the cursor to where you need it, using the A & D scales.

(If it’s more convenient, you can use the B & C scales the same way.)

To multiply, use C & D scales. Now at this point, let me mention that the trick that makes the slide rule work for multiplication, is that each number on these two scales is located at its („common,“ or, base-10) logarithm. The L scale, which runs from 0.0 to 1.0, and usually sits below the D scale, is exactly linear, being evenly divided all the way along. So if you set the cursor on any number on D (1 to 10), the log of that number (0 to 1) will be shown on L.

What this does is, by sliding the C scale „1“ over a number, a, on D, then reading what is on D below another number, b, on C, that result on D will be the product, ab.

C. . . . . . . 1 . . . . . 2 . . . 3. . 4 . 5. 6.7 8 91

D 1 . . . . . 2 . . .3. . 4 . 5. 6.7 8 91

With C=1 over D=2, you have C=2 over D=2•2=4, C=3 over D=2•3=6, etc.

This works because you have, in effect, added the logs of a and b, to find the number whose log is that sum. And

log(ab) = log(a) + log(b)

Similarly, with division, you slide the C scale number, b, over to the D scale number, a, and on the D scale under the 1 on the C scale, will be the quotient, a/b, because you have subtracted the log of b from the log of a.

Log(a/b) = log(a) – log(b)

With the setup shown above, you could be dividing, say, 8/4:

with C=4 set above D=8; below C=1, read the answer, D=2

The only other trick you need to know is, what happens when your result runs off the left or right end of the scale? For this, just note that you can use either index (the „1“s at either end) interchangeably. So move the cursor to mark your index that’s still within the scale, and slide the slide to put the other index at the cursor. Like, say you were taking 2•7 in that setup I showed a few lines up. The C=7 runs off over the right end of D, so slide the C back to the left, to put C’s right (instead of its left) index over D=2:

C 1 . . . . . 2 . . . 3. . 4 . 5. 6.7 8 91

D . . . . . . . . . . . . . . . . 1. . . . . . 2 . . .3. . 4 . 5. 6.7 8 91

which places the C=7 over D=1.4, representing 14.

So the slide rule does the „hard part“ of the math for you; but you have to keep careful track of any powers of 10.

That should be enough to get you up to the operations you asked about. Good luck!

Sharon asks…

## Was anyones stimulus tax refund from Bush not as much as they expected.?

Was your stimulus tax refund less than what you thought you were gonna get? Mine was and it was an **odd** number. Not 600 or 1200, like they said.

well ours was 1,029.00, we have one child and we filed jointly. Still don’t understand their figuring!

### admin answers:

Mine was $878; just right.

The IRS clearly explains that you’re eligible for a rebate of $300 UP TO $600 for single and $600 UP TO $1200 for MFJ.

The main factor is your tax liability. So, if you’re MFJ and your tax is $729, that’s what you get. Because your tax is over the minimum of $600 but less than $1200.

If you have any dependents under 17, you’ll get an extra $300 per child.

The IRS website has a stimulus calculator to help you figure your amount.

Nancy asks…

## what is the answer to this math equation?

Think of any positive whole number. If it’s **odd**, multiply it by three and then add 1. If it’s even, divide it by 2. Then take the new number and apply the same procedure. For instance, starting at 15, the sequence goes 15,46,23,70,35,106,53,160,80,40,20,10,5,16,8,4,2,1. It ended up at 1.

Now find the number that disproves this.

### admin answers:

I got 71, i did this number for 10 minutes on my calculator and the numbers on got higher. I’m not sure it is the answer or not though.

Maria asks…

## What’s the fastest way to find out how many complex zeros this function has?

The equation is f(x)= x^3-x+3.

Also, when is an quadratic equation reducible and when is it not?

oh, the confusion!

***sorry, I meant complex AND real zeros

### admin answers:

Every odd-degree polynomial with real coefficients has at least one real root. For a non-factorable polynomial like this, the easiest way is to graph it using a graphing calculator. You’ll see that it crosses the x-axis exactly once, so it has only one real root. The other two are complex. Check out sources for a good polynomial solver.

George asks…

## If i get paid 8 dollars an hour, then how much is taken out of that from taxes?

i live in illinois and i am 16. does that help? i kind of want an exact number

and what im trying to say is like out of 8 dollars what would be taken from that. like would i really be getting $7.34 or something like that

### admin answers:

You would need more information to get an exact answer. How many hours did you work? What is the pay period? (weekly, biweekly, etc) What are you claiming on your W-4 for your employer to calculate your federal tax withholding? What state do you live in? Are you in a city that requires local taxes to be withheld, if so what city?

You can gather your information and use the hourly calculator at paycheckcity.com. (http://www.paycheckcity.com/NetPayHRatesCalc/netpayHRatescalculator.asp) I’ve used it for odd paychecks and with worked well for me.

Federal (and most state) withholding is not calculated by the hour, it is calculated on the entire paycheck. FICA (Social Security and Medicare) is a percentage (7.65%) of your pay. Your hourly withholding depends entirely on how much you made in that pay period. Unless you work the same number of hours each pay period, your federal(and state) could be a different percentage each paycheck.

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