16
2x/8
8
No.
2d+8
You now have 8 doodads.
It is 80.
No. 4 is actually half of 8.
Twice.
Twice
Twice
Twice with a remaider of five
Twice with a remainder of two
Twice
Twice with a remainder of 3
twice as large 100% bigger
Twice
A Square has 4 sides, the shape you want that has twice as many sides as this is called a Octagon. ( Oct = 8 - as in Octopus ).