# Maths the key to perfect tree decor

### A FORMULA for the perfect Christmas tree has been devised by Sheffield students.

Maths undergraduates calculated the number of baubles, tinsel and lights needed to avoid bare branches - as well as the size of the obligatory star on top.

The formula, made up by members of the University of Sheffield’s maths society SUMS, will be used by department store Debenhams.

Nicole Wrightham and Alex Craig, both aged 20, were involved in the project.

Nicole said: “The formulas took us about two hours to complete.

“We hope they will play a part in making Christmas that little bit easier for everyone.”

Debenhams set the Christmas-themed challenge.

Store Christmas decorations buyer Sarah Theobold said the formula worked for all sizes of tree.

She added: “Customers often make the error of buying too large or small an angel, however this simple formula means you’ll have the ratio correct.”

The formulae are as follows:

■Number of eight centimetre tall baubles – The square root of 17, divided by 20, then multiplied by the tree height which is always in centimetres.

■The height of the star – divide the height of the tree by 10.

■The length of tinsel – 13 multiplied by Pi, divided by eight, multiplied by the tree height.

■The length of lights – Pi times tree height.