Remembering easy by: triangle shape set 1:( 3 planets )…. set 9(3 planets)= 9×3= 27 plantes:
TOTAL= 120 YEARS ( MAHADASHA)
MAHA DASHA/ ANTAR DASHA : current planet transit by dish maha dasha
HOW TO PREDICT VIMSHOTARI DASHA?Mahadasha-Antardasha Article
https://astrologywithsourabh.blogspot.in/2016/04/secret-of-maha-dasha-in-astrology-by_25.html
sample Mahadasha/Antardasha chart:
Astrology Blog -by Sudheer 