Oh Man!  I didn't know there was math involved in decorating a Christmas tree but there is.  We're going to put our up this weekend.  Click here to put in the hight of your tree & find out how many ornaments, lights & tinsel etc to have the "perfect tree" 

It was British people who figured this out so you'll have to convert from inches to centimeters.  Do that here cuz I have no clue.