Across
1
Mathematical rule or equation
3
Number divisible only by 1 and itself
5
Closed shape with straight sides
7
Divisible by two
8
Line touching circle at one point
Down
2
Difference between highest and lowest values
3
Parts per hundred
4
Steepness of a line
5
Lines that never intersect
6
The number representing nothing
9
Part of a line with two endpoints