Do we have to redo salah if we forget which rakah we're on?

So it's a common question that happens often at dhuhr or asr time. Are you on raka number three or raka number four? Now, there are two ways to look at it. Number one is that you could just go with the lower number. So just go with raka number three, continue, and then at the end of your salah, you pray the two extra sajidas known as sajid as-sahu. Or the second opinion is you would say, okay, is it more likely that I'm on raka three or four? If you think you're like 95% I'm on raka three, go with that. And then again, do the two sajidas at the end. And the same principle applies if you feel that you're on raka number four. Both views are valid. Either option is fine. The issue is flexible, inshallah.