Across
1
System of ordered marks for measuring
5
Rectangular array of numbers
6
Divisible by two
8
Value that does not change
9
Lines that never intersect
Down
2
Distance from center to edge of circle
3
Line touching circle at one point
4
Space between two intersecting lines
7
The number representing nothing
10
Part of a circle's circumference
11
Reference line in a graph
12
Line crossing from corner to corner
13
Round shape with all points equidistant
14
Number that divides evenly into another
15
Math using letters for unknown values