# How to write a sentence with the '=' symbol in it?

Does the following line sound okay when read out?

We choose the index n=5.

If not, how can I restructure it to make it a good readable sentence still with the '=' symbol?

I am trying to follow the rule that, sentences with mathematical notations in it should be readable.

• It doesn't sound right for a math paper. How about, "We let n be the index, and choose n = 5" ? Mar 31 '19 at 23:53
• If I read out your sentence as "We ... choose n equals 5", then it doesn't sound right to me. But, I am not a native speaker and it may be actually okay. If it read like "We choose n equal to 5" then it sounds right to me. But, "n=5" is a statement in itself, like "n is equal to 5" or "n equals to 5".
– AJS
Apr 1 '19 at 3:12
• You see "We let n = 5" all the time in math papers, and it's read "we let n equal 5," not "equals." So we would read it "and choose n equal 5," or maybe "and choose n equal to 5," not "and choose n equals 5." The rule that sentences with mathematical notations in them should be readable is not followed to the letter. Apr 1 '19 at 11:11
• Thinking about it some more, the reason that "we choose the index n = 5" sounds wrong to me isn't the equal/equals problem, but that it has two verbs. Consider the analogous sentence "We choose the boy Tom is the goalie." Apr 1 '19 at 11:18
• I think "we choose n equal to 5" makes sense. The equivalent way to say your example would be "We choose the boy Tom to be the gaolie". Two verbs used correctly don't always pose a problem. Thanks for your comments.
– AJS
Apr 5 '19 at 20:50

The convention is to not present equations in text but in numbered equations set off from the text. Only explain the symbols in text, e.g.

We added the number of women to the number of men to calculate the total number of persons:

m + f = p          (1)

where m is the number of men, f is the number of women, and p is the total number of persons.

In your case, where you don't give a complex equation but simply present the value of a variable, giving it in text is perfectly fine. I would simply rephrase your example a bit:

We choose an index of n = 5.

Use past tense ("chose") when you report what you have done and present tense ("choose") if you write a textbook instructing students what to do.

In general, the convention is to write words in text and to display equations, symbols, and numbers in figures, tables, or equations set off from the text. Number your equations, figures, and tables, so that you can refer to them in text, e.g.

We choose an index of 5 (see equation 1).

n = 5          (1)

• Many of your examples would be unconventional for 21st century mathematics and physics papers. In particular, your last example does not have the equation integrated into the text. In mathematics, you phrase and punctuate your equations more or less as though they were part of the text (as the OP remarks). On the other hand, for popular books on science, where you want as few equations as possible, and for them not to interfere with the text so that people can skip them, the conventions are quite different. You can treat them almost like figures, which is what you seem to be suggesting. Mar 31 '19 at 23:55
• @user10915156, thanks for the explanation. But, how would you read out your second rephrasing? Does "We choose an index of n equals to 5." sound correct as a sentence to you?
– AJS
Apr 1 '19 at 3:15
• @AJS My mother tongue is German. In German, the sentence "Wir wählten einen Index von n gleich 5" reads fine. I admit that I didn't consider how that sentence would read in English (as I learned maths in German and don't know how you would say many of the symbols in an equation), so very possibly a native English speaker would write that sentence differently. I'm open to corrections, and you are welcome to edit them into my answer, if you feel that is easily possible. Thank you.
– user37583
Apr 1 '19 at 13:31
• @PeterShor I'm a psychologist and not familiat with the conventions in Maths and Physics. As the asker didn't mention which field they are working in, and as I thought they should be familiar with the conventions in Maths if that was their field, I gave a non-mathematical answer. But see my first example, in which the equation is given as part of the text.
– user37583
Apr 1 '19 at 13:33
• @user10915156: You're right. It really depends on the field. Apr 1 '19 at 14:56