addend	A number added to one or more numbers to form a sum.
perimeter	The distance around a two-dimensional shape.
place value	The value of a digit based on its position within a number.
polygon	A closed plane figure bounded by three or more line segments.
regroup	Rewriting a number so you can subtract a greater digit from a lesser digit.
sum	The result when two or more numbers are added; the quantity that results from addition.