Across
1
Math using letters for unknown values
3
U-shaped curve of a quadratic function
5
Collection of distinct elements
6
Exact correspondence on both sides
7
Value that does not change
9
Three-sided polygon
10
Corner point of a polygon
Down
2
Single numeral from 0 to 9
3
Parts per hundred
4
Number that divides evenly into another
6
Result of addition
8
Sum divided by count
11
Part of a line with two endpoints
12
Middle value in an ordered dataset