# Area measurements

1. Aug 13, 2004

I need help converting feet to area or square feet for my horse stall. I have two stalls, each of which is 12' x 12'. I want to put a thickness of 2.25" of lime over the barn floor surface of these stalls. How many 50 lb bags would I need to buy? Can you show me the equation also? Thank you.

2. Aug 13, 2004

### humanino

looks very much like school homework, is it not ?
I unfortunatly don't understand foot, inch, or "lb" !
Convert everything in the metric system first !

3. Aug 13, 2004

### HallsofIvy

Staff Emeritus
It's easy to calculate that you will need 12x12x2.25= 324 cubic feet. The problem is that, in order to put this into pounds, you need to know the density of the lime.

Using, as a rough estimate, "a pint's a pound, the world around" (that really applies to water), 324 cubic feet is about 19390 pints. Roughing that out at 20000 pounds (perhaps lime is denser than water!), that would be 20000/50= 400 fifty pound bags.

4. Aug 13, 2004

### enigma

Staff Emeritus
You forgot to convert the 2.25" into feet.

12[ft] X 12[ft] X 2.25[in] X 1/12 [feet/in] = 27 ft^3

That's a cubic yard per stall. If you tell the guy you're buying the lime from that you need two yards, you should just make it.

Last edited: Aug 13, 2004
5. Aug 13, 2004

### humanino

Apart from the density, that was my missing step.
I can't understand the 1/12 stuff ! Where does it historically came from ?!
(I am aware that we are not using metric time either.)

6. Aug 13, 2004

### Zorodius

1/12 is a conversion factor - one foot = 12 inches. Apparently it was defined some time in the 1200's. Maybe it seemed like a good year for it?

Last edited: Aug 13, 2004
7. Aug 13, 2004

Replies to Area Math

Thank you one and all for your assistance.

8. Aug 13, 2004

### enigma

Staff Emeritus
1 foot = 12 inches,

so 1 inch is 1/12 of a foot.

2.25 inches are 2.25/12 feet

The trick to keep it straight is the units. There is 1 foot in 12 inches.

If you look at the 1/12 term, the feet are in the numerator, the inches are in the denominator.

If you multiply the units together along with the numbers, you can keep everything straight.

12 [ft] X 12 [ft] = 144 [ft^2]

2.25 [in] X 1/12 [feet/in] = 2.25/12 [(ft*in)/in] = .1875 [ft]

144 [ft^2] * .1875 [ft] = 27 [ft^3]

Last edited: Aug 13, 2004
9. Aug 13, 2004

### humanino

Thanks Zorodius

10. Aug 13, 2004

### enigma

Staff Emeritus
The reason why there are 12 inches in a foot is so you can have even measurements for 1/3 and 1/4 of a foot.

1/3 of a meter is 33.33333333333333... centimeters.

1/3 of a foot is 4 inches

1/4 of a cm is 2.5 mm
1/4 of a foot is 3 inches.

The reason that there are 60 minutes in an hour is because it is evenly divisible by
2, 3, 4, 5, 6, 10, 15, 20, and 30.

Degrees in a circle is even better.
360 is evenly divisible by
2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 18, 20, 24, 30, 36, 40, 45, 60, 72, 90, 120, and 180.

Obviously, more precision is necessary when navigating long distances at sea then when designing a stable. That's why there aren't 360 "quatloos" per foot.

IIRC, the Babylonians had a base 60 numbering system though...

Last edited: Aug 13, 2004
11. Aug 13, 2004

### Alkatran

I would argue that if you took 0.333333 instead of 12/4, that the difference once you reached your destination would be minute. It's entirely a convenience thing, not precision.

Oh, and any "perfect" precision is probably lost when degrees are converted to radians.