Tell me please if have to use "a" or "the" in the following dialogue:

Person 1: what did that tablet cost you?

Person 2: It costs 200 dollars. But I must say it is an/the approximate sum. My dad bought it me.

I think "the" should be used, but not sure. And Could I say it is an/the around sum?

  • 3
    correction: bought it for me.
    – Lambie
    Aug 1, 2018 at 18:58
  • I posted this below and it was deleted. So, instead of reposting it is as an below, here is it is, and shows that what I said is what LawrenceC says. ell.stackexchange.com/questions/157664/use-of-a-vs-the/… Yes, an approximate sum, first mention. Second mention: the sum.
    – Lambie
    Aug 1, 2018 at 21:32

3 Answers 3


Honestly, it's not the biggest error.
I'd concentrate more on number/tense agreement.
I'd also consider "bought it me" far too colloquial to use as an ESL.
I struggle using contractions like that & I'm a Northern Brit living in the South, where it would never be used at all.

I would recast the answer as

It cost [past tense] 200 dollars, but I must say...

  1. it [or that] is an approximate sum.
  2. that is the approximate cost.
  3. it's [that's] an approximation
  4. it's [that's] a guess

...My dad bought it for me.


Let's say the tablet actually cost $207.

$200 is one approximate sum, and $201 is another approximate sum. (You can continue this to come up with many approximate sums, depending on what number range you want to fit into your definition or approximate.)

Therefore, an is the correct word because there is no single approximate sum in the sentence you used, and $200 is just one of several possibilities you could have relayed.

However, the definite article would be correct in this sentence:

$200 was the approximate sum that I you about earlier.

Here, you only did relay to him a single approximate sum.


You can't use the X unless you were talking about X previously, or X is something observed previously by both parties in the conversation.

A good test - if the question "X of what" or "which X" makes sense, and both parties in the conversation can answer it, then you can say the X.

Person 2: It costs 200 dollars. But I must say it is an/the approximate sum.

Sum means "a total that is obtained when you add 2 or more things together" - and you haven't previously talked about a total of anything.

Where the confusion is: Sum does not mean "what X costs."

Person 2: It costs 200 dollars. But I must say it is the approximate cost.

You just mentioned cost in the first sentence. The question "cost of what" makes sense, and can be answered by both parties in the conversation.

So saying the approximate cost is fine.

  • It is an approximate sum. But it is not the sum I would have paid. This happens all the time in English. You move from a to the.
    – Lambie
    Aug 1, 2018 at 19:00
  • 1
    I don't agree that sum is completely incorrect. Definition 3 here is just "a quantity of money", which works even if it's not the best option. Aug 1, 2018 at 19:48
  • 1
    1. MONEY an amount of money: He owes me a large sum of money. LDOCE5 Aug 1, 2018 at 20:54
  • Idk, you can't say "Give me my sum" and it mean the same as "give me my money." Sum can mean money but won't imply cost like "How much money?" will.
    – LawrenceC
    Aug 1, 2018 at 20:56
  • This is about using "a" [some thing] the first time some thing is mentioned followed by "the" [thing], the second time it is mentioned. "He owes me a large sum of money". "The sum was agreed to by him when we discussed it." One moves in conversation from a thing to the thing. It is typical in English speech and writing. If everyone would take a breath and think about this, it will become evident.
    – Lambie
    Aug 1, 2018 at 21:34

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