The university’s Maths Society (SUMS) was given the challenge by department store Debenhams: decorate a Christmas tree in such a way that to perfectly balance the decorations. Properly done, there should be no bare branches; the formula also provides for calculating the size of the topping star.
Students Nicole Wrightham and Alex Craig, both 20, created the formulas. Sorry, those in the U.S. Since this was created in the U.K., it uses the metric system. The formulas are:
Number of baubles: Take the square root of 17, divide it by 20 and multiply it by the height of tree (in centimeters).
Length of tinsel: 13 multiplied by pi (3.1415926535) divided by 8, then multiplied by tree height.
Length of tree lights: Pi multiplied by tree height
Height (in centimeters) of star or fairy on top of tree: Tree height divided by 10.
For those in the U.S., an inch is 2.54 centimeters.
As an example: a 180cm (six-foot) tall Christmas tree would need 37 baubles, around 919 cms of tinsel (30 feet) and 565 cms (19 feet) of lights. It would need an 18cm (seven-inch) star or angel to achieve the perfect look.
Debenhams Christmas decorations buyer Sarah Theobold added (considering they commissioned the study and have something invested in it):
The formula is so versatile it will work for a tree large enough for the Royal Family at Balmoral, but also on trees small enough for the most modest of homes.The University calls this new math treegonometry.
Customers are often making the error of buying too large or small an angel; however this simple formula means you’ll have the tree to star ratio correct.