easy sum...

The Long Count aka TLC

Kin............1
Uinal..........20
Tun............360
Katun.........7200
Baktun........144000
Great Cycle........ 1872000 'days' = 5125 'years', 'ending' December 21, 2012, Winter Solstice

13 x 20 = 260 Mayan Sacred Tzolkin
18 x 20 = 360 Mayan Tun

20 x 20 = "vision"

1872000 / 1300 = 1440 / 4 = 360
1872000 / 1800 = 1040 / 4 = 260
............................difference = 100 Mayan
............................ 0400 'The' difference

1872000 / 400 = 4680 and this going >> this direction = 8640
and by coincidence, 86400 = 'seconds' in 1 day ... one additional 'zero'

back to  4680 / 13 = 260
and also 4680 / 18 = 360