You find the area of one side of the cube which is 12.25 mm and multiply it by the number of side which is 6. and the answer is 73.5 mm
The answer to what is 1,000 to the power of 4 is 1,000,000
I’m not sure what happened while you were writing this, but if I’m reading it right, “My” has 18 books. If “My” has 3 times as many as 6, that also means 3 times 6, which is 18.