Across
1
Reference line in a graph
3
Total distance around a shape
6
Part of a whole number
7
Mathematical rule or equation
9
Number with digits after a point
11
The number representing nothing
Down
2
Corner point of a polygon
4
Line segment connecting two circle points
5
Rectangle with four equal sides
8
Difference between highest and lowest values
10
Number divisible only by 1 and itself
12
Exact correspondence on both sides