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Discussion Starter · #1 ·
Sorry if this is in the wrong sec...Im looking into better understanding elevations and i can't seem to find the anwsers im looking for.
If FF is 670.87 and i need to excavate to 623.2 what is the difference in feet? 47ft 1/4 inch?
 

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47.67" or 47 11/16"
Welcome to CT. Just a heads up, do an intro in the introductions section and if you haven't filled out your profile do that too.
 

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thanks...one question still.....i understand how you arrived at 47.67 but im unaware of how you got 11/16 out of .67...sorry im a newb in this area of const.
No problem. Math is a crucial part of every single trade in construction. (as well as management)

I'll work on a post right now to demonstrate how this works, in the meantime, please fill out your profile including area and do an intro. I'll post back in a few minutes.
 

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You figured out how to get down to inches in decimal form. In this case 47.67 You just need to learn how to make that into something you can read on a tape measure.

What you do is enter 47.67 into any calculator, then deduct 47 (you already know it's 47 inches and some change) leaving you with .67

Next you need to know how specific you need to be. If you want the results down to 32nds of an inch, simply multiply .67 by 32 which will give you 21.44. Round that number either up or down depending on the numbers after the decimal. 21.44 will round down to 21 then you have the fraction of 21/32.

If you want your result in 16ths, multiply the .67 by 16 leaving you with 10.72. Round that up to 11 then you have the fraction of 11/16

If you want your result in 8ths, multiply the .67 by 8 leaving you with 5.36. Round that down to 5 then you have the fraction 5/8

Etc.

Hope this helps.
 

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Those are tenths and hundredths.

47.67 is 47.67 feet, the .67 is out of a foot.

Site work is usually done with a engineers scale in which feet are divided by tenths and hundredths. Muxh easier to work this way than with inches, especially when you are trying to calculate slope, etc.

.1 tenth is 1.2 inches, 12 inches divided by 10. So .67 is actually 8.04 inches. Normally you would never have to covert back and forth from tenths and inches.
 

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Sorry guys. I should have noticed that. OK-beat me up. I deserve it.

I'm so used to working in feet and inches (smaller scale) that I overlooked that. I was just demonstrating how to turn inches in decimal form into a fraction.

I'll step out. I misunderstood the OP's question. Sorry
 

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Pug, I can answer your question correctly now that I understand it. Just multiply the remainder (now in feet-.67) by 12 because there are 12" in a foot.

.67 x 12 = 8.04. Round that down to 8. That's where the 8 inches come from.

Sorry, I know I said I'd step out but I owed the help to the OP to correct my advice.;)
 

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Figure a hundredth (.01) is
roughly an eighth of an inch.
Conventional conversions are...
1" = .08
2" = .17
2" - .25
4" = .33
5" = .42
6" = .50
7" = .58
8" = .67
9" - .75
10"= .83
11"= .92
12"=1.00

Close enough for dirt
and surveyors. :thumbsup:
 

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neolitic, when I first started I used to write those conversions on the plans so I wouldn't forget it. I would also convert all the 10ths into inches on the plans because my first grade stick was in 12ths and not 10ths. I now own a grade stick that is engineers scale.
 

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neolitic, when I first started I used to write those conversions on the plans so I wouldn't forget it. I would also convert all the 10ths into inches on the plans because my first grade stick was in 12ths and not 10ths. I now own a grade stick that is engineers scale.
It's easy to memorize.....
once you do it a few
hundred thousand times. :laughing:
 

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Vagitarian
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WTF are you digging that you are going that deep ?
 

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Just multiply the decimal part by 12.
Engineers scale. Decimal feet is a LOT easier to perform math on than fractional feet. I hope whatever king decided to divide a foot by 12 is rotting in hell. Engineers tape measure is nice sometimes, graduated in 10th and 12th. Just make sure you use the right side ;)

daveosborne.com/dave/articles/decimalfeet.php
 

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Discussion Starter · #20 ·
Figure a hundredth (.01) is
roughly an eighth of an inch.
Conventional conversions are...
1" = .08
2" = .17
2" - .25
4" = .33
5" = .42
6" = .50
7" = .58
8" = .67
9" - .75
10"= .83
11"= .92
12"=1.00

Close enough for dirt
and surveyors. :thumbsup:
Great post bro...just wondering if you or anyone would clear up another question i have.....say for example im working with .83 12=9.96". I see you rounded that up to 10....what if i had to be more acurate then within an inch.....say to the 1/8 of an inch....would i multiply by 8...so .96x 8=7.68 so 7/8.....is this on the right line of thinking?
 
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