Across
1
The number representing nothing
3
Math using letters for unknown values
4
Exact correspondence on both sides
8
Steepness of a line
11
Corner point of a polygon
Down
2
Proven mathematical statement
5
Part of a whole number
6
System of ordered marks for measuring
7
Divisible by two
9
Distance from center to edge of circle
10
Number divisible only by 1 and itself