What should a latecomer do in prayer if he doubts the number of prostrations while making up what he missed?

If someone doubts in their prayer whether they performed one prostration or two, and they are not prone to frequent doubts, then they should base their action on the lesser amount, considering themselves to have performed one prostration. They should then perform the second prostration, and subsequently perform the two prostrations of forgetfulness (sujud al-sahw) before the salutation of peace (taslim). As for someone who is prone to frequent doubts, they should disregard whatever they doubt.