25 Years - 18 Years Rahu + 7 Years Ketu of 120 Years of Human Life

 Rahu and Ketu do not own any signs, but they do own nakshatras, and hence are assigned appropriate dasha periods in the Vimshottari dasha system. 

1. Rahu owns Ardra, Swati and Shatabisha and has 18 years 
2. Ketu owns Ashvini, Magha and Moola nakshatras and has 7 years out 

of 120 years of Vimshottari dasha period.

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