Across
1
Total distance around a shape
5
Collection of distinct elements
7
Part of a circle's circumference
8
Part of a line with two endpoints
11
Mathematical rule or equation
Down
2
Number that divides evenly into another
3
Result of addition
4
Single numeral from 0 to 9
5
Rectangle with four equal sides
6
Longest side of a right triangle
9
Rectangular array of numbers
10
Symbol representing unknown value