Across
1
Part of a circle's circumference
3
Split into equal parts
4
Sum divided by count
6
Collection of distinct elements
8
Result of addition
9
Power to which a number is raised
10
Lines that never intersect
11
Number that divides evenly into another
Down
2
Number less than zero
5
Part of a whole number
7
Line touching circle at one point
8
Steepness of a line
12
Round shape with all points equidistant
13
Number divisible only by 1 and itself