5

How to read this to others, so they can write it down just by listening?

1 + (-2) = -1

Also:

1 - 2 = -1

I want to know the differences.

16

How you explain this really depends on how much you want to convey, and how much you think will be assumed. For instance, the most specific wording of the first example would go something like this:

One plus open parenthesis negative two close parenthesis equals negative one.

The second example would be as follows:

One minus two equals negative one.

The important difference (pun intended) is how to say the '-' sign. I have found, contrary to the other answers so far, that a '-' when used on only one number (such as on the right side of those equations) is referred to as a 'negative' operator, whereas when used on two numbers it's a 'minus' sign. Saying 'two plus minus one', to me, implies 'plus or minus', which might not apply in most contexts but is definitely worth avoiding. On the other hand, 'two plus negative one' is immediately clear to me.

This even makes the parentheses in your first example unnecessary, and you can just say

One plus negative two equals negative one.

Unless you actually want everyone to write down the parentheses, in which case you should be explicit.

  • 3
    You woudn't happen to be american, would you? In the rest of the world, we do tend to use "minus" to refer to a negative number. "Negative one" sounds incredibly obtuse to my ear. – fabspro Dec 23 '15 at 15:25
  • 3
    (not to negate the answer, because it is very valuable to touch on the fact that 'negative' can only be used in the unary sense, but 'minus' can be used for both). – fabspro Dec 23 '15 at 15:28
  • 1
    @fabspro Yes i am American. Using 'minus' for everything sounds really confusing to me, especially in text. Maybe with the right emphasis it can be clear what operator you're referring to, but i think using 'negative' avoids that problem altogether. – DaaaahWhoosh Dec 23 '15 at 15:39
  • 3
    From my undergrad experience in math and CS at an american a school, negative one is vastly more common (I dont recall ever hearing "minus one". So it might be regional.) If I heard "plus minus one" I'd think of ±. – Senjougahara Hitagi Dec 23 '15 at 23:44
  • 1
    @DaaaahWhoosh it's turned out to be an interesting discussion point - minus versus negative for the unary operator. I think we've both had our eyes opened a little to the regional differences. – fabspro Dec 27 '15 at 1:30
7

As a maths teacher, I would accept any of the following as correct (listing my most preferred reading first):

1 + (−2) = −1

One plus negative two equals negative one

One plus minus two equals minus one

One add negative two equals negative one

(Other arrangements of "negative" versus "minus", and "add" versus "plus", are also possible, although I'd be a little bemused if someone said "negative two" and then "minus one"!)

Other readings are, of course, possible, although I would regard something like "the sum of one and minus two is minus one" as an interpretation, or maybe a paraphrase—describing the meaning, rather than reading it as written.

1 − 2 = −1

One take two equals negative one

One subtract two equals negative one

One take away two equals minus one

One minus two equals minus one

This last one illustrates the potentially confusing status of "minus" as both "something done to two numbers" and "a type of number" (in grammatical terms, both a verb and an adjective; in mathematical terms, both a binary and a unary operation).

4

There's no much difference on those examples.

For example the second one is read as one minus two equals minus one. The first one can be read similarly (one plus minus two equals minus one), but having something like 1 - (1 - 2) = 2, that's different, you need to say there's a bracket, and then that's one minus, open bracket, one minus two, close bracket, equals two. You can also use parenthesis.

  • Wouldn't you say bracket only for [...]? – Massimo Ortolano Dec 23 '15 at 19:35
  • 2
    Brackets can cover (),{},[], & <> in my experience. The last are called "angle brackets" and generally appear in mark-up languages. – JB King Dec 23 '15 at 20:46
3

In the first example, i would personally say

One plus [pause] [quickly] minus two [pause] equals minus one

Depending on my mood, i might say "negative" instead of "minus".

It's shorter than saying aloud "parenthesis/bracket", but still conveys the separation.

I've never had anyone complain about it being hard to understand, at least not with short expressions.

A slightly more complex example to explain:

1 + (2 * 3) = 7

One plus [pause] [quickly] two-times-three [pause] equals seven

But

(1 + 2) * 3 = 9

[quickly] One-plus-two [pause] times three equals nine

2

You could simply say :

One plus minus two is equal to minus one.

and

One minus two is equal to minus one.

Logically, there is no difference between the two expressions. I'm sure you're aware of that. Generally brackets () are used to avoid confusions with the arithmetic operators. If you want to know more about the mathematical aspects of the expression, you should ask the same questions here. The math geniuses there will certainly help you. In these expressions, you need not specify the brackets as they are mostly used only for written purposes and not used verbally. Additionally, you could swap 'is equal to' with 'equals'.

  • 1
    I would say "negative two" instead of "minus two"... – Alex K Dec 23 '15 at 3:49
  • 1
    That's a regional thing, I say negative as well. – modulusshift Dec 23 '15 at 7:03
  • 1
    FWIW, I'd go with minus (but accept it's regional). – TripeHound Dec 23 '15 at 10:48
1

You can say, with emphasis on the bolded part,

One plus minus two inside bracket equals one

and

one minus two, equals minus one

  • It's not at all clear what your "inside bracket" applies to. – David Richerby Dec 23 '15 at 18:58
  • well, when we say emphasize on bold one, we mean to stop after 'One plus', and then say the whole phrase together so that other person understand, "minus two inside bracket". And it can't be explained further. – Divyanshu Dec 24 '15 at 7:16
0

Well, over here (Nigeria) it is quite different as it reads:

1 + (-2) = -1

one plus open-bracket minus 2 close-bracket equal-to minus 1

  • That is how you literally read each character aloud. But this how teachers teach in schools and you don't use terms like "open-bracket" when an expression is used in a non-curricular context. – Varun Nair Dec 24 '15 at 6:11
0

I know this doesn't sound grammatically right.

I remember my Math teacher saying something like

1 + (-2) = -1

One plus of minus two equals minus one

And

1 - 2 = -1

One minus two equals minus one

But then this is Math! It's a wholly different language by itself!

  • "One plus of minus two" really does not sound right. Where was this? – Nathan Tuggy Dec 24 '15 at 7:30
  • This was an Anglo-Indian teacher who taught Math at my school in India. – Caroffrey Dec 24 '15 at 7:44
-1

the first for me would be the sum of one and negative two is negative one

the second would be: the difference of two from one is negative one

  • 1
    Please edit to include an explanation of why this is correct; answers without explanation do not teach the patterns of the language well. – Nathan Tuggy Dec 23 '15 at 22:28

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