Method 1

150,5*7= 1116,5

This method is very imprecise.

Method 2

A1B1      =    B1C1
AB          =    BC

1000       =    X  
70           =    70

1000/70  =   X/70
70           =    70

1000       = X

This method is more difficult but more precise.

Method 3

We havent made this because its not sunny anymore in Denmark...
This method is not easy to make because there is not any sun. but it is the most precise.

The high of the tree is ca. 1000 cm tall.
We think that the best method is number 2 because you can always make it and it is almost precise.