Punctuating letters

[Grammarholic]

1 or 2 below when punctuating individual letters or numbers?

Are both forms correct (technically), yes or no?

His 'b's look like 'd's. His '3's look like '8's.

OR

His b's look like d's. His 3's look like 8's.

Thanks.

[/i]

[Our Tort System]

I vote for
His b's look like d's. His 3's look like 8's.
Compare it to http://www.usingenglish.com/reference/idioms/dot+all+the+i%27s+and+cross+all+the+t%27s.html
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[Thirdgoblin]

The second one is correct. It's something like cross your t's and dot your i's.