Block number, for short? Crossword Clue

 The answer to the crossword clue "Block number, for short?" is SPF.

The acronym SPF stands for sun protection factor. It is a measure of how well a sunscreen protects the skin from the sun's ultraviolet (UV) rays. The higher the SPF, the greater the protection.

SPF is often used in crossword puzzles as a short way to refer to a block number. This is because the number of letters in the word "SPF" (4) is the same as the number of letters in the word "block" (4).

Here are some other words that could also be used for the crossword clue "Block number, for short":

Blk

No.

Bldg

Unit

Blg

Bl

I hope this helps! Let me know if you have any other questions.