Across
1
System of ordered marks for measuring
3
Exact correspondence on both sides
4
Symbol representing unknown value
6
Three-sided polygon
9
Line touching circle at one point
Down
2
Number with digits after a point
3
Part of a line with two endpoints
5
Parts per hundred
7
Distance from center to edge of circle
8
The number representing nothing
10
Mathematical statement of equality
11
Single numeral from 0 to 9