Suppose someone says:

Hey, can you help me solve this algebra problem?

What should I say if I want to use the word forget?

  1. Sorry, I forget how to do algebra.
  2. Sorry, I've forgotten how to do algebra.
  3. Sorry, I forgot how to do algebra.

My confusion is between those three. I believe I can use the simple present since what I'm saying is true and it's a fact. However, [2] and [3] seem to be true as well at the same time, I can't tell why.

2 Answers 2


I would say #1 or #2 is fine:

  • I forget how to do algebra: Puts the act of forgetting in the present. Maybe you do generally know it, but you can't remember right now, so you can't help.

  • I've forgotten how to do algebra: that is, sometime between when you learned algebra and now, you've forgotten how to do it. The act of forgetting is somewhere in the past but you still haven't remembered again.

Either of these are natural ways to explain it. Personally, I'd only use the simple past — I forgot — if it's something I forgot in the past, but also something that I normally know or have remembered since then:

  • I worked with Mark for five years. I'm so embarassed that I forgot his name when I went to introduce him to someone else.

  • I practiced the dialog from The Phantom of the Opera for weeks, but I got stagefright & I forgot my lines as soon as I got up on stage.

  • 5
    Yes, this is correct. If in the course of conversation you're talking about some guy and you say I've forgotten his name, the implication is you'll probably never remember his name again unless someone reminds you of it. But Present Tense I forget his name would often imply ...but I might well remember it on another occasion. Note that it's unlikely you'd say I forgot his name unless you were specifically referring to some point in past time when you couldn't remember the name (even if at current time of speaking you know perfectly well what it was). Oct 11, 2021 at 17:41
  • I think it might be worth pointing out that "I'm sorry, but I forget how to X" has a subtext of "I'm lying and I know perfectly well how to do X, but I don't want to help you so go away", and "I forget his name" has a subtext of "I remember his name, but I'm pretending to have forgotten it to insult him".
    – nick012000
    Oct 12, 2021 at 6:46
  • 2
    @nick012000 Context is key: If I make a judgement call that there's no way what the speaker is saying is true, I might read that subtext into it, but I think that's just true of lying in general, rather than specific to the word 'forget'. E.g. if I start at a new company at the same time as someone else & they say "Sorry, I can't help you file your timesheets, I forget how to use the system myself", I wouldn't think there's any malice there. If they said "Sorry I can't give you a lift to the team lunch, I forget how to drive" it would be different! Oct 12, 2021 at 9:37
  • 1
    +1 The simple past might also imply that you've since remembered - it can be ambiguous also. For example, "I forgot to bring the cake!" is something you might exclaim precisely at the time you've just remembered that you were supposed to bring the cake, and is so generally in "I forgot [to do something]" statements.
    – J...
    Oct 12, 2021 at 19:30

They all are correct, but the meaning is a bit different.

"I forget how to do algebra" means that there's some regularity to that; that you need to do some algebra from time to time, and every time you can't remember how to do it.

"I've forgotten how to do algebra" means that you have forgotten it some time ago. For example, you last did some algebra in school, and ten years passed since then, and you haven't done any algebra since then, so you have forgotten how to do it.

"I forgot how to do algebra" is the simplest one, it doesn't say anything about how frequent it happens, or how long it's been since you knew. Just the simple fact that you knew, but right now you don't.

  • 3
    I would expect "I forgot how to do algebra" to be followed by something like "long ago" or "after I left school". Oct 11, 2021 at 15:53
  • 1
    "I forget" seems quite common amongst young people in SE England for more normative "I forgot". Bugged the hell out of me when I was in school and all my friends would say it
    – Tristan
    Oct 12, 2021 at 13:45
  • 1
    If the regularity aspect is important then it should better be “I keep forgetting how to do algebra”. Oct 12, 2021 at 16:45

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