Unexpected difference

Question

I was messing with some algebra and got an unexpected gap.  Here's the different equations:

 

(112.5*2.125)/2+(122.5*3.225)/3+(132.5*4.325)/4+(142.5*5.425)/5)/4 got a similar answer to:

 

(112.5*1.125)+(122.5*2.225)/2+(132.5*3.325)/3+(142.5*4.425)4)/4

 

BUT, when I tried:

 

(162.5*2.625)/2+(172.5*3.725)/3+(182.5*4.825)/4+(192.5*5.925)/5)/4 compared to

 

(162.5*1.625)+(172.5*2.725)/2+(182.5*3.825)/3+(192.5*4.925)/4)4 was much different than expected.

 

Any guess why

Answer 1

1.  These are NOT EQUATIONS.

2.  They are numerical expressions, evaluated on a calculator according to PEMDAS rules.

3.  What do you mean by similar results?

4.  What did you expect?

5.  In each unrelated case, I would say that the result follows the"It is what it is" principle.