Math Professor’s ‘Christmas Tree Lights Spacing Calculator’ Creates Perfectly Lit Christmas Trees

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MOBILE, Ala. – A University of Mobile mathematics professor has solved one of the frustrations of the Christmas season by developing the Christmas Tree Lights Spacing Calculator that anyone can use.

Dr. Troy Henderson, professor of mathematics, developed the online calculator after he and his wife, Greta, were faced once again with figuring out how to evenly space lights on their tree without running out too soon or having too many left over.

“This year we were too greedy with the lights at the bottom of the tree, and therefore we were in need of too many lights at the top to ‘tweak’ the spacing for complete coverage. We were forced to either pull the lights off and start again or purchase another strand of lights,” Henderson wrote in a blog on The Torch, the digital magazine of University of Mobile.

They bought more lights, but the problem of uniform spacing still troubled him.

“As a mathematician and a problem-solver, I still wanted to know the optimal spacing of the lights so that the distribution is uniform and the precise number of lights are exactly used without tweaking them,” he said.

The online calculator uses the diameter of the Christmas tree at its base, the height of the tree, and the length of the strands of lights on hand. Input the numbers, and the calculator computes the vertical spacing you should have between rotations, the number of rotations you will have, and creates a picture demonstrating the result.

The Christmas Tree Lights Spacing Calculator is just one example of how Henderson challenges students to see mathematical problems in everyday life, and to have fun and a sense of personal accomplishment in discovering solutions. The professor has also worked out a mathematical model for the cooking process of smoking barbecue.

Henderson’s blog with a link to the Christmas Tree Lights Spacing Calculator is at


About University of Mobile:
University of Mobile is a Christ-centered liberal arts and sciences institution with a vision of higher education for a higher purpose, founded to honor God by equipping students for their future professions through rigorous academic preparation and spiritual transformation. Core values are: Christ-Centered, Academically-Focused, Student-Devoted and Distinctively-Driven. The university offers on-campus and online bachelor’s and master’s degree programs in over 40 areas of study. Founded in 1961, University of Mobile is affiliated with the Alabama Baptist State Convention and is located 10 miles north of Mobile, Alabama on a campus of over 880 acres. For more information about University of Mobile, visit the website at or call Enrollment Services at 1.800.WIN.RAMS or 251.442.2222.

About the Author
Kathy Dean

Kathy Dean

Kathy is an award-winning media relations director and former journalist whose expertise has enabled the University of Mobile to gain national and regional attention. She holds a Bachelor of Arts in Journalism from Auburn University and worked as a journalist for 12 years, including 10 years at the Mobile Press-Register, earning regional and national awards for coverage of education, deadline reporting and feature writing. She joined the University of Mobile staff in 1993, earning awards for writing and public relations including the Baptist Communicators Association grand prize for feature writing in 2015 and 2012. She is a charter member of Providence United Methodist Church, serves on the board of the John Will Scholarship Foundation, and is a member of the Public Relations Council of Alabama, Baptist Communicators Association, and Society of Professional Journalists. Kathy lives in Daphne with her husband, Chuck, who earned his M.B.A. from the University of Mobile. They have two children and two grandchildren.

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