A&A.org calc isn’t as precise, but does show a .1% chance of all 3 units being lost in 3 rounds.
Actually, that’s easy to calculate by hand…
(1/6)^3 = .00463, or .5% chance that your 1 hits 3 in a row.
(5/6)^2 * 1/2 = .34722, or 34.7% chance of whiffing in a round
.34722^3 = .04186 or 4% chance of whiffing 3 straight rounds.
.04186*.00463 = .00019 that both would happen (the result you saw)
That’s .02% chance, or 1 in 5,000 which is pretty rare, as you would suspect.
The 1,111 was the chance the 2 infantry and fighter would be lost, but the bomber not necessarily surviving round 3.
The 1 in approx. 5,000 is the bomber surviving and hitting 3 straight times.
Many calculators are going to show 100%, not 99.98%. Or as pancake said, will runs X number of battles and give results. But even then, it could be subject to rounding.
Again, there is no such thing as a 100% battle when dice are to be rolled (only defenseless AA guns or transports are 100%)