Test your knowledge of the international 10-20 system!
15cm
18cm
21cm
23cm
F4
Cz
Pz
C3
7.2cm
6.8cm
10.8cm
8cm
13cm
18cm
15cm
16cm
F4
F8
Fz
P4
29cm
27cm
18cm
35cm
20.5cm
14cm
18.2cm
16.4cm
T4
P4
O2
T3
11cm
6.5cm
5.5cm
4.4cm
F7
P3
C3
T5
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