When you hear somebody say something that you know is wrong, you want to tell them. Here are ten polite and less polite ways of telling them they're wrong.

I'm afraid that's not quite right.
Actually, I think you'll find that...
I'm afraid you're mistaken.
I don't think you're right about...
Actually, I don't think...
No, you've got it wrong.
No, that's all wrong.
Rubbish!/You're talking rubbish.
Where did you hear that?
If you check your facts, you'll find...

Explanations

• Phrases 1 and 2 are fairly polite. If you really want to be polite you could make an apology first e.g. 'I'm sorry to disagree, but...'
• Phrases 3 and 4 are a little stronger and a little less polite.
• You follow phrase 4 with a noun phrase or a gerund.
• Phrases 6 and 7 are very strong. You may upset the person you are talking to so you should be really sure about your own facts before you say one of these.
• Phrases 8 and 9 are actually quite rude. Even people who know each other quite well may not say these phrases to each other.
• Phrase 10 is followed by a sentence or clause with the correct information.