Across
1
Line touching circle at one point
3
Reference line in a graph
4
Mathematical rule or equation
5
Rectangle with four equal sides
8
Value that does not change
10
Steepness of a line
Down
2
Distance from center to edge of circle
4
Part of a whole number
6
Difference between highest and lowest values
7
Repeated addition
9
The number representing nothing
11
Number divisible only by 1 and itself