(11.0-12.3)^2+(10.7-12.3)^2+(13.1-12.3)^2+(13.9-12.3)^2+12.9-12.3)^2+(12.5-12.3)^2)++(11.9-12.3)^2+(12.4-12.3)^2

I think you have some problem while typing

(11.0-12.3)^2+(10.7-12.3)^2+(13.1-12.3)^2+(13.9-12.3)^2+(12.9-12.3)^2+(12.5-12.3)^2+(11.9-12.3)^2+(12.4-12.3)^2

=(-1.3)^2+(-1.6)^2+(0.8)^2+(1.6)^2+(0.6)^2+(0.2)^2+(-0.4)^2+(0.1)^2

=1.69+2.56+0.64+2.56+0.36+0.04+0.16+0.1

=8.11