Answer:
(Fatwa: 709/497/L=1431)
(1) If you have any doubt regarding the number of fasts then follow the maximum numbers i.e. if you do not remember whether you missed 30 fasts or 35, then keep 35 fasts.
(2) While keeping fast, make intention that you are doing qaza of fasts of so and so year and if you do not remember year then on every fast you should make intention of doing the qaza of first or last missed fast.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband
