Dial / Speedometer Chart - Segment (Pie) Proportions and Accuracy of Dial

HI
Since we want to start at 10% and finish at 20% I created a donut chart where 10 parts
they have the same size (10) and one part is equal to the sum of the previous ones.
I assigned the numbers 10 to 20 as labels.
The pie chart takes data from cells G3:G5. In these cells there are the following formulas:
cell G3 =SE(O(H3<0,1;H3>0,2);"Error";((H3*100-10)*180/10)-G4/2)
report error if entered number less than 10% or greater than 20%
cell G4 =360-SUM(G3:G4)
round angle minus the sum of start and width

Hi,
Mario