Across
1
Result of multiplication
4
Number divisible only by 1 and itself
7
Total distance around a shape
9
Line crossing from corner to corner
11
Space between two intersecting lines
12
Line touching circle at one point
Down
2
Math using letters for unknown values
3
Value that does not change
5
The number representing nothing
6
Collection of distinct elements
8
Round shape with all points equidistant
10
Lines that never intersect