- 41 → 133: +92: 41 → 133
- 133 → 173: +40: 133 → 173
- 173 → 371: swap digits: 173 → 371
- 371 → 386: +15: 371 → 386
Today's chain starts at 41 and has to finish on 386 in exactly 4 moves, each tile used once.
The hand: +15, swap digits, +92, +40, +14. +15 moves you up by 15; from 41 that is 56. swap digits turns 41 into 14 straight away, and it changes digit count when a number ends in 0. +92 moves you up by 92; from 41 that is 133. +40 moves you up by 40; from 41 that is 81. +14 moves you up by 14; from 41 that is 55.
First, +92: 41 → 133. This is the move that crosses 100. Then +40: 133 becomes 173. That leaves 213 still to gain. swap digits next, taking 173 to 371. That leaves 15 still to gain. +15 next, taking 371 to 386. It lands exactly on 386.
Working backwards helps: the chain can finish on +40 or +15; take +15, which turns into 386 from 371. So the real question is how to reach 371 in 3 moves from 41 with the remaining tiles.
Step by step, the choices narrow: At 41, 5 tiles are legal and 2 of them still lead to 386. At 133, 4 tiles are legal and 2 of them still lead to 386. At 173, 3 tiles are legal and 1 of them still leads to 386. At 371, 2 tiles are legal and 1 of them still leads to 386.
Why not +14? Put it in for +15 and the chain ends on 385, 1 below the target — a near miss, but a miss.
In total there are 4 ways to land within 10 of 386 without hitting it, and 4 orders of the right tiles that do hit it.
Once the set of tiles is right, the order usually follows from what is legal at each step.