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Agriculture is ‘sweet spot’ where math, real world problems mix

Agriculture is ‘sweet spot’ where math, real world problems mix

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Kids who don’t enjoy math often ask, “When will I ever use this?” Teachers attempt to give real-world examples, and students remain skeptical.

Scholastically, word problems are the key to real-world application, but I don’t know any kid who adores word problems. Numbers and words may as well be oil and water.

Agriculture is a sweet spot where math meets real world. My husband isn’t fond of math and yet his calculation ability is sharp because he uses it every day of every season.

He figures cattle rations to get the correct weights of various feeds in the feed wagon, determines seed spacing, checks the custom applicator’s final spray rate, calculates a ballpark yield by counting ears and uses a formula for figuring loss behind the combine.

He always carries with him a nearly worn-out pocket calculator, scrap of paper and a pen, and sometimes a reference guide such as an Extension guide.

Such tools are useless if you don’t know how to use them. (Kids, pay attention in math!)

I’m a math geek married to a farmer and my interests skew in those directions, maybe more than is socially acceptable. Calculations that, literally, are some people’s bread (there are 23 ounces of wheat in a grocery-store loaf) and butter (one stick comes from approximately 5 pounds of milk) are fun trivia for me.

Years ago as a freshly minted commercial driver’s license holder waiting in a long, long line of trucks at the Coors elevator in Monte Vista, Colo., I coaxed my sister into asking the elevator manager how much barley was used for a single can of beer. Answer: About 1.53 ounces.

Using that figure and the numbers on my scale ticket, my sister and I calculated that our truck held the raw material to make 63,666.67 cans of beer.

Beer can number that big interest many people — farm kids and town kids alike — and also was small-talk gold for an introverted math major at a small college in central Kansas.

Here’s how to do the math.

Test weight for Coors’ proprietary malting barley is about 54 pounds per bushel. A typical semi load is about 1,000 bushels. So the formula is: (54 pounds per bushel) (1,000 bushels)(16 ounces per pound)/(1.53 ounces per can) = 564,706 cans.

Here are some other fun calculations.


My husband keeps back one steer from each year’s calf crop for our family to eat later. Meat is a high-dollar food item for our household of seven and this makes a lot of sense for us.

What should you expect in meat when buying a beef animal and having it processed at a nearby locker? Averages are helpful for planning, but the yield always is a bit of a surprise.

Approximately 61.5 percent of a live animal goes into meat processing (hanging weight).

Depending on the cuts and parts you prefer to use, take-home weight is about 55 percent of hanging weight. That goes up if you take home parts such as the heart, liver, fat to make tallow or bones for broth.

We typically have a steer butchered at age 2 and 1,200-1,350 pounds.

So, the calculations are: (1,300 pounds)(0.615) = 799.5 pounds hanging weight. Then, (799.5 pounds)(0.55) = 439.7 pounds of take-home meat.

We expect half to be ground beef, but we also come home with brisket, T-bones and a bunch of other great food.


My fact-finding mission led me to the websites of Sierra Pacific Industries, whose sawmills and kilns provide moisture-stabilized incense cedar wood to pencil manufacturers, and to Dixon Ticonderoga, manufacturer of pencils I like.

I used a ruler and a caliper to measure a hexagonal Ticonderoga pencil. It is 7 inches long with a diameter of 0.285 inches, of which part is the paint on the pencil.

Cedar boards are cut into slats. Two slats then are sandwiched together around graphite leads and cut out to make pencils.

Taking a thin saw blade into consideration, 3-inch-wide slats would permit cutting 10 pencils across.

In an error- and defect-free scenario, a 3-inch by 3-inch by 10-foot board would make 17 blocks of wood 7 inches long. So each block would make 100 pencils, for a total of 1,700 pencils.


My brother and sister-in-law’s December wedding was in the Texas Panhandle at a venue surrounded by cotton fields of future jeans. It had been many years since I’d been in cotton country at picking time.

For this calculation, I used the USDA’s National Agricultural Statistics website and a blog by Janet Person, an agvocate.

Cotton plants produce two products, lint and seed, which are separated at the gin.

In 2017, Texas growers’ produced an average of 793 pounds of cotton lint per acre of harvested cotton.

I weighed a pair of my jeans. At 18.8 ounces and 71 percent cotton, they contain about 13.3 ounces of cotton.

So, 793 pounds is 12,688 ounces. That means in a waste-free scenario, Maurices could make approximately 954 pairs of size 9/10 DenimFlex boot-cut jeans from the 2017 production from one typical Texas acre.

That’s a new pair every day for almost three years. I’d run out of closet space.

Freelance editor and designer Karen Nelson writes four times a year from her rural Phelps County home. She welcomes comments and discussion at


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