I have some trouble getting this small problem right

I want to make a plane from these three points:

1

5.004.218 993.185 9.591

2

5.005.202 993.397 12.622

3

5.006.043 993.715 10.325

I have made two vectors from these points

1-2

984 212 3.031

1-3

1.825 530 734

and then calculated the normal vector to these two vectors

n

-1450822 4809319 134620

and from this I have tried to get the equation to the plane which the three lays onto

plane

-1450822 4809319 134620 -2,48239E+12

I want to calculate the distance from the plane to a fourth point

4

5.020.399 933.806 9.908

I have the made this

7,28371E+12 4,49097E+12 1333814960 2,48239E+12

and this to get the distance

(7,28371E+12 + 4,49097E+12 + 4,49097E+12 + 2,48239E+12)/ sqroot(-1450822^2 + 4809319^2 + 134620^2) = 2837385,029

Can someone please have a look at my calculations so far, and tell me what I have done wrong? (I know the answer is wrong...)

I have made it in a excel spreadsheet if someone would look at it