Water + Water = Lake
Lake + Lake = Ocean
Fire + Water = Steam
Earth + Water = Mud
Mud + Fire = Brick
Brick + Brick = Wall
Wall + Wall = House
House + House = Town
Town + Town = City
City + City = Country
Country + Country = Continent
Continent + Continent = Planet
Planet + Planet = Star
Star + Star = Galaxy
Galaxy + Galaxy = Universe
Universe + Universe = Big Bang
Big Bang + Big Bang = Number
Number + Number = Numbers