The answer depends on how many letter tiles you have and which letters are on those tiles.
210 tiles
4.
49 tiles
250 tiles
There are two (2) blank tiles in standard Scrabble with an assigned value of zero points.
2 blank tiles
2
Seven (7) letter tiles (blank inclusive, if any).
EngNoPointsA101B24C24D52E121F24G33H34I91J110K15L41M23N61O71P24Q110R61S51T71U42V24W24X18Y24Z110
They're for any letter you want. If you place it, you can choose what letter you want it to be. :)
The blank tiles may be used as any letter desired. When playing a blank, the player must state what letter it represents, after which it can not be changed during that game.
The blank tiles can be used as any letter.
The number of sites that contain the word friends is actually uncountable.
The game contains 100 tiles: 98 are each marked with a letter and the point value of that letter and there are 2 blank tiles that can be used as any letter. There are 100 letter tiles.
blank tiles that do not contain a letter
You can use the blank tiles to represent any letter you like. When you play the letter, you tell the other player what the letter represents. It stays the selected letter as long as the blank tile remains on the board.