MU
Worth 4 points before any premium square, and the 34th highest-scoring of 96 — tied with 18 others.
MU extends into 8 three-letter words, which is the 34th least extendable of 96 — tied with 7 others. That is the number worth memorising: a two-letter word is a place to put tiles, but a well-hooked one is a place to put them where the board stays open.
Every hook
- A→AMU
- E→EMU
- D→MUD
- G→MUG
- M→MUM
- N→MUN
- S→MUS
- T→MUT
Not all of them are equally reachable, which a bare count of 8 hides. MU hooks on 8 distinct letters, and the ones you are likeliest to be holding are E (60% of opening racks), A (49% of opening racks) and N (36% of opening racks). The rarest is M, at 14%.
How often you can actually play it
Out of an opening rack, 3.06% of the time you hold the letters for MU outright, the 12th least likely of 96 — tied with 4 others. Counting a blank as whichever letter is missing lifts that to 7.41%, though spending one of the two blanks on a two-letter word is rarely the play. Exact hypergeometrics over the 100-tile bag, not a simulation.
It reverses
MU backwards is UM, which is also good. That is how most of this list is actually learned — 46 of the 96 come in reversible pairs, so knowing one gets you the other free.