Hello everyone! I have read similar posts but I'm still not sure about one thing about the use of present perfect and past tense. Let me put it in an example to clarify what I mean. Does it have to be a 'result' or 'effect' on now if we are using the present perfect? Suppose I'm in a class and we are having a lesson, the teacher reminded us over and over again to bring our calculator today. But I realise I didn't bring it and I don't the calulator so I say to my friend "Oh my god! I forgot to bring my calculator! / I have forgotten to bring my calculator." - I understand we can use either past or present perfect tense in this case, depending on our style. But what if the day ends and I go back to home and my mom asks me how my day went so I say to her, "I have forgotten to bring my calculator!" - Is that idiomatic? I'm not sure whether people would use the present perfect here (Because now I'm home and not having a calculator does not affect me anymore). I think using past tense here is more common, even in BE. I hope you know what I am asking. If not, please tell me. Thanks!