Apologies for repost, but this is such a great solution that I thought
I'd repost it with as many keywords as possible. I had some difficulty
finding this post. Credit goes to Dave Peterson back in 2003.

Keywords: tick check checkmark in cell checkbox without checkbox

And here's Dave's solution:

Select your range that will get the check marks.
Format it to use Wingdings font.

Then (with the range still selected), hit Format|Cells|Number
Tab|Custom:

Use a custom format of:
ü;ü;ü;ü
(I use alt-0252 from the numeric keypad--not above the QWERTY keys to
make those
funny symbols.)

<alt-0252 semicolon alt-0252 semicolon etc

No matter what you type into the cell, you'll see a checkmark.

If you have to refer to it later to see if it's checked, you can use a
simple
formula like:

=if(a1="","not checked","checked")