I have heard British people speak about "hard sums," but I can't find a definition anywhere. Is it just a generic way of referring to any arithmetic that the speaker believes is difficult? Or does it have a more specific definition or nuance?

If someone says "I can do hard sums," what does that mean exactly?

  • Why are all the answers getting downvoted? Commented Jun 23, 2011 at 13:06

3 Answers 3


"Hard sums" is used to mean "difficult mathematics" in a self-deprecating way, depending on the speaker.

If someone says

I can do hard sums.

and they are:

  • A four year-old: It means they've started doing addition.
  • An eight year-old: It means they've mastered multiplication.
  • A high-school student: It means they can do some simple calculus.
  • An undergraduate: It means they can do more complex calculus / analysis / algebra.
  • A post-graduate: It means they're Einstein. :-)

And each group is more self-deprecating than the last.

  • So it's just a way of saying "difficult math"? No specific idiomatic meaning? Not even a nuance? Commented Jun 23, 2011 at 4:52
  • 3
    AFAIK, the only nuance is what I mentioned: it's self-deprecating.
    – Peter K.
    Commented Jun 23, 2011 at 11:48
  • @Down-voter: Feedback on why you down-voted appreciated!
    – Peter K.
    Commented Jun 23, 2011 at 11:54
  • Interesting. When I saw this used, it was speaking to a broad audience with a presumably wide range of math levels, so it seemed like it must refer to something specific. Also interesting that it means any kind of math. The word "sums" gave me the impression that it referred to arithmetic. A bit disappointing that it has such a bland meaning, but thank you. :-) Commented Jun 23, 2011 at 12:46
  • 1
    @no one special: I'm sorry to disappoint! My perspective is from when I was an engineering grad student who used to hang around with mathematics grad students. Others may have a different view. In general, the math grad students found bistromathics harder than what they did for a living. :-)
    – Peter K.
    Commented Jun 23, 2011 at 12:55

It is a vulgar / slang metaphor expressing confidence in one's ability to cope with a difficult situation or to do something difficult, not just [literal] hard mathematics.

Usually in response to a sceptic asking: "Are you sure you can cope / do that thing?" It is usually phrased as: "Yea, no problem, I can do [the] hard sums! / hard math!"

I cannot find a reference to back up my personal experience, but I have a feeling that it is a bastardisation of a US idiom, that has been adopted, spasmodically in the UK, probably as the result of some usage in a Hollywood film.

  • Difficult things - but specifically of an analytical nature, right? I don't think you'd use it to describe a hard physical problem, like lifting or fighting or playing the oboe. Nor for a situation that was intellectual but non-analytical, like debating or writing prose. What do you think?
    – SusanW
    Commented Feb 16, 2022 at 10:52
  • Hi Susan, [personally] I don't think this term is ever used literally, it is used metaphorically to mean: "I have confidence in my ability..." to do whatever the thing is.
    – NeilB
    Commented Feb 17, 2022 at 17:24
  • Hi Susan, [personally] I don't think this term is ever used literally, it's a metaphor used to mean: "I have confidence in my own ability...". "You do the math!" is usually used to mean stop being stupid and think about the problem yourself! "I can do the hard sums" is [not very often in my UK experience] used dismissively if someone asks: "Are you sure you can do that [task]?" or "Do you need me to help you with that [task]?", the answer could be: "No thanks, I can do the hard maths." - I can work it out myself. It could be applied literally, but more often ironically, to ANY task.
    – NeilB
    Commented Feb 17, 2022 at 17:40

It would be nice to get a bit more context. Before I read the other answers, I actually thought hard sums might refer to concrete or verified calculations, as in cold, hard facts, or hard numbers. If these hard sums are sums of money, for example, then we can talk about hard dollars (in the U.S.), which are objectively quantifiable sums (like the number of dollars it would cost to buy a new computer system); versus soft dollars, which are not so objectively quantifiable (like the value of productivity losses or low morale endured while switching to the new computer system).

Edit: Now that I've got the context, I see that my answer doesn't apply. Please see the other responses that have to do with "difficult arithmetic".

  • Two examples I've heard: 1) "Most people don't realize that quilting requires doing hard sums." 2) From the show Black Books, "He can speak nine languages, blow glass and do hard sums, but he wouldn't tell you. He's just so modest." Commented Jun 23, 2011 at 4:49
  • @no one special: Ah, then yes, the other folks who have said it was just "difficult mathematics, expressed humbly" have the meaning you are after.
    – John Y
    Commented Jun 23, 2011 at 16:26

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