Across
1
Number greater than zero
5
Single numeral from 0 to 9
8
Proven mathematical statement
9
Number less than zero
10
Distance from center to edge of circle
12
Sum divided by count
Down
2
Exact correspondence on both sides
3
Part of a whole number
4
The number representing nothing
6
System of ordered marks for measuring
7
Result of multiplication
11
Power to which a number is raised
13
Middle value in an ordered dataset