A big mac is a burger that has 563kcal.
A grand big mac(sold in limited area) is 764kcal.
A grand big mac is said to be 1.3 times as big as a big mac. Actually, 764/563=1.357, so we can consider that the 1.3 means calories.
But to be simple, we assume calories like this:
Big mac - 563kcal
Grand big mac - 732kcal
And we consider that a grand big mac is geometrically similar to a big mac, just 1.3 times bigger in volume.
But why am I talking about hamburgers? This is a googology website. Don't be worry, "usual" googology starts here.
Grand grand big mac would be 951.
(I removed units because this is not hamburger-ology but googology)
Grand grand grand big mac or trigrand big mac would be 1,237, which is bigger than a giga mac.
tetragrand big mac would be 1608.
Keep going on...
Pentagrand big mac, hexagrand big mac, heptagrand big mac, pctagrand big mac, nonagrand big mac, decagrand big mac, ... ,icosagrand big mac, tricosagrand big mac, centagrand big mac, milligrand big mac,......
Who stops here?
Let's throw all the hamburgers away and get into pure googology.
563-grand big mac= big mac grand big mac
next, big mac grand grand big mac
and then, big mac trigrand big mac
somehow, big mac big mac grand grand big mac
great big mac = 563 nested "big mac grand" big mac