C.A.T.S.Crunchy Automated Tactical System

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Exploding d6 Resolution

Every 6 is re-rolled and added, recursively. Computed exactly from the closed form up to a total of 120; residual truncated mass is reported below and is negligible.

A total of exactly 6, 12, 18, or any multiple of 6 is impossible on a single die, because a 6 always explodes. This leaves visible gaps in a single-die distribution that fill in as dice are added.

Summary

DiceMeanMedianNo die explodesResidual mass beyond 120
1d6!4.2383.3%6.7e-016
2d6!8.4769.4%1.4e-014
3d6!12.61157.9%3.0e-013

A plain d6 averages 3.5. Exploding raises that to 4.2 per die — a 20% increase — and adds an unbounded right tail.

Chance of rolling at least a given total

Total1d6!2d6!3d6!
3+66.7%97.2%100%
5+33.3%83.3%98.1%
7+16.7%58.3%90.7%
9+11.1%38%75.5%
11+5.6%25%57.4%
13+2.8%16.7%42.1%
15+1.9%10%30.3%
18+0.5%5.1%17.1%
21+0.3%2.3%9.3%
25+0.1%0.8%3.9%
30+0%0.2%1.2%

The tail

Exploding dice have no maximum. These are the probabilities that make the tail real rather than theoretical.

Dice2x mean or better3x mean or betterChained explosion (2+ in a row)
1d6!11.1%2.78%2.8%
2d6!6%0.64%5.5%
3d6!3.1%0.18%8.1%

Depth tiers — hit location by explosion chain

A single exploding d6 partitions itself into exact tiers of five, separated by the unreachable multiples of 6. Reaching tier N requires N-1 explosions, so deep locations are unreachable without them.

TierResultsExplosions neededEach resultTier total
11-5016.667%83.333%
27-1112.778%13.889%
313-1720.463%2.315%
419-2330.077%0.386%
525-2940.013%0.064%

Tier totals form an exact geometric series that sums to 1: 5/6, then 5/36, then 5/216, and so on. The unreachable multiples of 6 are not a defect here — they are precisely the boundaries between layers.

Full distributions

1d6 exploding

TotalChanceAt least
116.67%100%
216.67%83.33%
316.67%66.67%
416.67%50%
516.67%33.33%
6impossible16.67%
72.78%16.67%
82.78%13.89%
92.78%11.11%
102.78%8.33%
112.78%5.56%
12impossible2.78%
130.46%2.78%
140.46%2.31%
150.46%1.85%
160.46%1.39%
170.46%0.93%
18impossible0.46%
190.08%0.46%
200.08%0.39%
210.08%0.31%
220.08%0.23%
230.08%0.15%
24impossible0.08%
250.01%0.08%
260.01%0.06%
270.01%0.05%
280.01%0.04%
290.01%0.03%
30impossible0.01%

2d6 exploding

TotalChanceAt least
22.78%100%
35.56%97.22%
48.33%91.67%
511.11%83.33%
613.89%72.22%
711.11%58.33%
89.26%47.22%
97.41%37.96%
105.56%30.56%
113.7%25%
124.63%21.3%
133.7%16.67%
143.01%12.96%
152.31%9.95%
161.62%7.64%
170.93%6.02%
181.16%5.09%
190.93%3.94%
200.75%3.01%
210.57%2.26%
220.39%1.7%
230.21%1.31%
240.26%1.11%
250.21%0.85%
260.17%0.64%
270.12%0.48%
280.08%0.35%
290.04%0.27%
300.05%0.23%

3d6 exploding

TotalChanceAt least
30.46%100%
41.39%99.54%
52.78%98.15%
64.63%95.37%
76.94%90.74%
88.33%83.8%
99.03%75.46%
109.03%66.44%
118.33%57.41%
126.94%49.07%
136.25%42.13%
145.56%35.88%
154.94%30.32%
164.4%25.39%
173.94%20.99%
183.09%17.05%
192.55%13.97%
202.08%11.42%
211.72%9.34%
221.45%7.62%
231.29%6.16%
240.99%4.88%
250.78%3.89%
260.62%3.11%
270.49%2.49%
280.4%2%
290.35%1.6%
300.27%1.25%

Source: docs/analysis/exploding-d6.md — this page is generated from it.