Ten of them.
16
Two groups of five is ten
144
there are 10 groups of 10
Ten.
Your Mother
''Decagon'' is any polygon with ten sides and ten angles ''Regular decagon'' is a polygon with ten sides of equal length and all angles equal to 144°
10
One thousand.
There are 73 groups of 10 and 1 left over, or 73.1 groups of 10.
Thirteen of them.