I'm starting to recall some weird "order of operations" stuff that might be what's going on here.
 
As I said... I am now curious (and a little ticked off that I can't remember this type of thing... time for some math courses).
 
FRIGGEN MATHZ!!!!

So udder
Many amaze
Wow
 

My eyesight may be poor today, but my math is correct.

The standard calculator that comes with Windows shows the incorrect answer, while the Scientific one (same app) is correct.  More info:
 
Different calculators follow different orders of operations. Many simple calculators without a stack implement chain input working left to right without any priority given to different operators, for example typing
 
        1 + 2 × 3 yields 9,
 
while more sophisticated calculators will use a more standard priority, for example typing
 
        1 + 2 × 3 yields 7.

craigb
My eyesight may be poor today, but my math is correct.

Whoomp... thar it is...
 
For example, in mathematics and most computer languages, multiplication is granted a higher precedence than addition, and it has been this way since the introduction of modern algebraic notation.[1][2] Thus, the expression 2 + 3 × 4 is interpreted to have the value 2 + (3 × 4) = 14, not (2 + 3) × 4 = 20.
 
craigb is right... it's 15.
 
Totes forgot about the OoO.
 

It's still a double quarter-pounder combo.

Of course, Paulo probably noticed that the second box of fries in each part of line 3 is slightly higher indicating that it is fries raised to the fries power.  That makes fries equal to about 1.56 (1.56 ^ 1.56 = 2.00) which makes the final answer 20.6.
 
That must be what he saw.  Sharp that guy is I tell ya! 

Dammit, Jim!
 
We're musicians... not math talking guys!
 
serios tho... now i've got in my craw to fix this massive math gap in my brain goop
 
that ain't cool

Can't help it.  Having been a programmer for over 46 years now order of operations is seared into my jelly-like brain.  Of course, my programs rarely compile clean on the first try, so there is that issue...