Ignorance of the Amount of Missed Obligations

Question

A person was neglecting prayer and fasting at certain times at the beginning of their religious obligations and does not know exactly how much they missed. What is required of them? [AR_ID:816]

Answer 1

Peace be upon you. According to Sayyid Sistani and Sayyid Khamenei, it is obligatory to make up for all the prayers and fasts that one is certain to have missed after reaching the age of religious obligation.