What is the best way to write something like 6.22E-21 in LaTeX, given that I don't want the numerals to be \tt, I do want the E to be small, and I may want the exponent to be negative (without the huge LaTeX minus sign)?

I'm sure this is a duplicate of another question that I just can't find.

Example here:

## Best Answer

For a one-off implementation of your typesetting needs, you could try

This will work in both text and math mode. If you use the

`amsmath`

package, you should typeas this is slightly more general than the first solution. Specifically, it'll work better if the expression ever occurs in scriptstyle (first-level sub- and superscripts) or scriptscriptstyle (second-level sub- and superscripts) material.

Conversely, if you have a lot of numbers that you wish to typeset in this way, you should implement a solution along the lines provided in @AlfC's answer. Otherwise, sooner or later some inconsistencies in the way you typeset these numbers will creep in.