You don’t need to use an apostrophe to show the plurals of symbols.
Examples: #s 1, 2, and 3 (numbers 1, 2, and 3)
$s, not €s (dollars, not euros)
For information on apostrophes with numbers, dates, and letters, click here.
An inquisitive reader asked the following question:
When do you use on to vs. onto?
Answer: Use onto as one word if you can add up before on.
Example: He climbed (up) onto the roof.
Example: She held on to her child in the crowd. (She did not hold up her child.)
Click here to learn hundreds of distinctions [...]