Name 
Number of Sides 
Interior Angle Measure 
Central Angle Measure 360/number of sides 
Triangle 
3 
60° 
120° 
Quadrilateral 
4 
90° 
90° 
Pentagon 
5 
108° 
72° 
Hexagon 
6 
120° 
60° 
Heptagon or Septagon 
7 
128.5° 
51.4° 
Octagon 
8 
135° 
45° 
Nonagon or Enneagon 
9 
140° 
40° 
Decagon 
10 
144° 
36° 
Hendecagon or Undecagon 
11 
147.2° 
32.72° 
Dodecagon 
12 
150 
30° 
Triskaidecagon 
13 
152.3° 
27.69° 
Tetrakaidecagon 
14 
154.2° 
25.71° 
Pentadecagon 
15 
156° 
24° 
Hexakaidecagon 
16 
157.5° 
22.5° 
Heptadecagon 
17 
158.82° 
21.17° 
Octakaidecagon 
18 
160° 
20° 
Enneadecagon 
19 
161.05° 
18.94° 
Icosagon 
20 
162° 
18° 
Triacontagon 
30 
168° 
12° 
Tetracontagon 
40 
171° 
9° 
Pentacontagon 
50 
172.8° 
7.2° 
Hexacontagon 
60 
174° 
6° 
Heptacontagon 
70 
174.85° 
5.14° 
Octacontagon 
80 
175.5° 
4.5° 
Enneacontagon 
90 
176° 
4° 
Hectagon 
100 
176.4° 
3.6° 
Chiliagon 
1000 
176.64° 
.36° 
Myriagon 
10,000 
179.96° 
.036° 
ngon 
n 
(n2) × 180° / n 

You can make names using Number of sides
For example 40 Tetraconta 
+1 henagon +2 digon +3 trigon +4 tetragon + 5 pentagon +6 hexagon +7 heptagon + 8 octagon +9 enneagon

Tetracontakaihenagon =41 sides Tetracontakaidigon =42 sides Tetracontakaitrigon = 43 sides 
