Across
1
Distance from center to edge of circle
4
Number divisible only by 1 and itself
5
Single numeral from 0 to 9
8
Collection of distinct elements
10
Divisible by two
11
Middle value in an ordered dataset
Down
2
Total distance around a shape
3
Part of a whole number
6
Value that does not change
7
Line crossing from corner to corner
9
Split into equal parts
12
The number representing nothing