Math Cheat Sheet

[Guido]

I think when I get some spare time this looooong weekend, I'm going to make a math cheat sheet for new guys ( and some old ) in the business since a lot of people usually have trouble with this. I'll e-mail it out and put it on my website too.

Do you guys have any ideas of what all I should include? I'll do the conversion stuff and Cu. Yds., apshalt and concrete, Weights of used products, inches to feet chart, and some other stuff. Let me know if you guys have any other ideas.

[Guido]

Let me know if its missing something. I just threw it together quickly for now. I'll improve it after sugeestions and put it somewhere on my home page.



Guido Asked that I remove the old document.
paul, moderator

[eskals]

Guido:

Looks like a good start.

On this line: Area of a circle = Pi(3.14) x Radius x Radius

I would just say 3.14 x radius x radius

The way it is written now, it could be interpreted as 3.14 x 3.14

Also, might not be a bad idea to include somewhere on the sheet that when making calculations, you must always have the same units. EG. You can't multiply inches and feet and get something meaningful.

Eric

[stslawncare]

very good start, may also want to incorporate a soil chart, mulch chart, etc etc. the more of the math that u do, the more resourceful it will be, i have found a decent soil chart, but im still looking for that perfect paper or papers that do all the math for me for all the different materiales of all the sizes weights etc etc etc

[Dennis]

Guido

9sq ft = 1 cu yd ?? Am I missing something?
Also could you include how to work with bags of Mat. from Garden store, by using Examples. As in 100 Sq ft of mulch using 2 cu ft bags,I work better seeing examples,bad in math.
Thanks
Dennis

[paul]

Why do you need one for soil and one for mulch, both are Cu. Yd measures?

[Stonehenge]

Here are a few thoughts -

Always specify units when giving formulas. When you have a formula for volume, specify the units, so someone doesn't multiply inches and feet. Do that on every formula.

And you can't divide yards by 1.3 and get meters. There are 100 centimeters in a meter. There are 2.54 cm in an inch. Therefore, there are 39.37 inches in a meter. This is 1.094 the length of a yard. So, multiply yards by 1.094 and you get meters.

[Ron Persaud]

I find it useful to write all the measurements in the same units from the very first time. If I have to mulch a strip 100 yards long by 3 feet wide to a depth of 3 inches, I might decide to calculate in feet.
The measurements now become 300ft by 3ft by 3/12ft.
cu.ft. = 300 x 3 x 3 (2700)and divide the answer by 12. (225)
If a bag has 2 cu.ft. then estimate for 113 bags.
If you need the answer in cu.yd. then divide the cu.ft. by 27.
If you play around with some simple things it is amazing how not-so-simple they are. Calculate the volume of a cardboard box and then take it apart carefully. Now calculate the area of cardboard it took to make the box.

And quickly now, which has more fenceline? A square or oblong piece of property with the same square footage?:)

[Guido]

Okay, Just got back from my mini-vacation to Amsterdam, so I'm still a little hazy, but when I wake up, I'll fix my typo's on that sheet and try to organize it better.

Thanks for the feedback guys, let me know if there is anything else you would like to see.

[Guido]

Okay, I fixed a few typos I had, changed all the conversions from metric to standard and standard to metric. Added a chart for inch to decimal conversions. If you downloaded the first one, please download this one to replace the file you d/loaded earlier in the thread.

ESKALS - Yeah, I thought the circle one was confusing the way I wrote it, should have just kept it simple, I changed it now though. Again, I should have kept it simple and said to make sure to keep all of the units the same, noted that in the revised one too. Thanks for the help!

STS LAWNCARE (SCOTTIE) - Those are all Cu. Yd. Measures. They are all pretty much the same. The only variation I've seen is to add .05% when ordering concrete to make sure you have enough in case of voids in your base course or for crete that slips under your forms, etc.

DENNIS - Your right, it was a typo! Sorry about that! As far as your request, you can just figure out the area and then divide by how many bags. For example if you have to do a 100 Cu. Ft. Area and your bags spread 5 Cu. Ft., than you would need 20 bags of material.

PAUL - Thank you Paul, as always!

STONEHENGE - Okay, not sure what happened but we were both wrong, I think. I think I have it down right this time though, check it out and let me know. Thanks!

RON - Your right, we can make anything complicated! It does get crazy after you think about it too long, thats why I'm trying to make it easier for some that don't feel comfortable doing the math.

Now, for your trick wuestion, its the same amount of fence, right? ;)


Okay Guys, let me know if you see anything else you want fixed or added.

Thanks Guys!

[Ron Persaud]

Not quite.
Consider 3 properties 10,000 sq.ft.each.

100' x 100' = 10000sqft. 400 ft. fence.
200' x 50' = 10000 " 500 ft. "
400' x 25' = 10000 " 850 ft. "
The more "square" it is, the smaller is the distance around it.
The more oblong, it will be greater.

[Guido]

Thats what the wink was for, I didn't want to give the answer away. My wife was sitting here and argued with me about it until I drew it out on paper to explain! :)

[Stonehenge]

You're right -

I had the units reversed on the yards to meters. Good illustration of why you always need to specify units.

But I still don't get the last part -

The area of anything can't equal the volume of anything ... X sqft = X Cubic Yd.

[stslawncare]

hey, this sheet is getting better and better, i noticed u have the equation of a yard of crushed stone is so many tons. well how about that same thing for soil, mulch, etc (even the specifics such as humus, top soil, potting soil, mushroom soil, compost etc) i figure the more of the math that is done and on this paper the better, my goal is to help u dave and between the two of us get all the math done and written down into a packet of conversions and charts. sound good? the less math we have to do at a jobsite when giving an esitimate the better u know :-))

[HOMER]

Do sod man, please do sod again. That way next time I won't buy a pallet and a half too much!

[Guido]

Okay!

Scottie (STS) - You either own or have a close connection to "Nutra Soils" You sell the stuff!!! Tell me how much it weighs per ton and I'll put it in their!! Do you guys have a scale? Does anyone weigh their loads? Maybe on an invoice when you purchase it my the ton?? Try to figure out what the stuff weighs and I'll put it on there.

Homer - I'll try to do some research on the sod. I'll try to find both large and small rolls and squares. If anyone knows how much is on a pallet and the approx size, etc, let me know and I'll put it in there.

Thanks Again, and let me know what else I'm missing in there!

[stslawncare]

1 yd. weighs 1 ton (as received fresh)(fresh compost)
1 yd. Will cover 650 square ft. at ½” depth and 215 ft. at 1 ½” depth.

heres a start, trying to get a wheel with all the info from my uncle (boss/owner), btw im just a internet sales manager (representitive)

[lawnboykb]

Man you need some cool stuff like bluegrass has 950,000-2,000,000 seeds per pound. Tall Fescue 220,000 seeds per pound.
Or that clay weighs per cubic foot 105-120 wet and 90-110 dry, gravel 120-135, peat moss loose 3-5, sand dry 95-110 wet 120-130.
Or soil permeability rules, that sand with one inch of water will cover in depth 12" loam 6", clay 3".
What about angles of repose...I'm sure that a lot of guys know this stuff sand dry 20-30 loam 20-40 gravel 30-50.
Or volumes of sand or gravel in stockpiles with about a 37 degree repose 10'-68cy, 15'-230, 20'-550.
What about excavated soil and the swelling factors....sand 1.15, sandloam 1.20, clay loam 1.30 or just clay 1.35 don't any of you guys factor this stuff in?
Or lets go the other way shrinkage sand 1.18, sandy loam 1.23, clay loam 1.43, clay 1.48.
Hey what about straw? At 1" it will cover 200sf 2"-100sf and so on. Do any of you know what a nursery container weighs? 1 gal 7lbs 5-40 15-188...or do you just throw them into the truck until the springs bend south?
What about some good old trig to find out how many cubic yards you have in that pile of dirt….or take about going from inches to feet and how to do it.
I do most of this all day long, most of the guys I work with laugh because I stand around with a calculator running numbers during lunch and all my breaks…..but one things for sure I never have a lot of waste! And I NEVER come up short on a job. NEVER in the end this is the kind of stuff that saves you a lot of money.

Do any of you know how many acres of grass your mower will mow in an hour? And how much gas it will require? And how many it takes before an oil change? I bet no one here can cut what my mower can. I can get 7 yes 7 acres in one hour……

[Ron Persaud]

Too glib, man! Too many variables like width of cut, ground speed and length of run between turns. Ground speed in turn is dependent upon obstacles, berms and slopes, height of turf/cut and wet/dry ground conditions.
A 72-inch mower travelling in a straight line on dry,level ground at 10 mph is cutting 7.28 acres per hr.

6ft. x 5280ft.(1 mile) x 10 mph / 43560 (sq. ft. in an acre)=7.2727 ac.