Across
1
Line segment connecting two circle points
3
Number less than zero
7
Symbol representing unknown value
9
Part of a line with two endpoints
12
Lines that never intersect
Down
2
Single numeral from 0 to 9
4
Distance from center to edge of circle
5
Part of a whole number
6
Round shape with all points equidistant
8
Split into equal parts
9
Exact correspondence on both sides
10
Number with digits after a point
11
Math using letters for unknown values
13
Number divisible only by 1 and itself