Megafugafive is equal to \(5\uparrow\uparrow5\), or 5 tetrated to 5. It is approximately equal to 1010102184 or E2184#3 in Hyper-E notation. Googology Wiki user Hyp cos calls this number pentbo, and it's equal to s(5,5,2) in strong array notation. This number is also equal to s(5,2,3), s(5,2,1,2), and s(5,2{2}2).