The total interior angles of a hexagon = 720°

Each time we add a side (triangle to square, square to pentagon, pentagon to hexagon) we add another 180°.

Triangle to hexagon

Triangle		Square		Pentagon		Hexagon
$180°$	$+$	$180°$	$+$	$180°$	$+$	$180°$	$=$	$720°$

The total internal angles of a hexagon = 720°

The total interior angles of a hexagon equals 720 degrees

Now divide the total internal angle by the number of corners.

i.e. divide 720° by 6.

$720^circ/6=120^circ$

1

2

3

4

5

6

$120°$

$+$

$120°$

$+$

$120°$

$+$

$120°$

$+$

$120°$

$+$

$120°$

$=$

$720°$