Spacing of plus-or-minus sign (±) when used with percentage?

Question

I have a question regarding the correct spacing of plus-or-minus sign (±) in a specific situation.

Normally there should be a space on both sides of the sign, e.g., A ± B. If I want to express “20 percent plus or minus 3 percent” it could be 20% ± 3%. But what if I want to omit the first percentage sign for conciseness? Should it be:

1. 20±3%, or
2. 20 ± 3%?

I personally prefer the first one, because the second one could also mean 20(an integer) fluctuate within 3%, i.e., 19.4-20.6?

I couldn’t find the answer anywhere. Thank you in advance for answering the question.

Answer 1

This is a typesetting, rather than a mathematical issue, but I'd prefer the latter, personally.