Five numbers, three darts each, doubles only to finish: ladder #263 asks for 12, 51, 62, 83 and 105.
12 is a straight double: D6. If the dart lands in the single by mistake you are left on 6, which still has a double finish with the darts you have left. 51 is a two-dart finish: 11 D20.
62 is a two-dart finish: T18 D4. 83 is a two-dart finish: T17 D16. 105 needs all three darts: T17 14 D20. If the first dart misses its treble, the board will show the new route straight away.
At best the five finishes need 10 darts out of 15. Your result counts the finishes you make first and the darts you used second. These are friendly numbers. Aim at the inside half of the double on the first dart — a miss on that side lands in the single and keeps the finish alive.