Ask The Wizard #125
Do you have tips for wagering on a coin toss?
Certainly! My suggestion is to place your bet on the side facing up at the beginning of the toss. Based on research, Science News Online the chance of a coin landing on the same side it started is around 51%. This is due to the fact that when a coin is flipped, it doesn't rotate perfectly around its axis, which creates the illusion of continuous flipping. This theory holds true only if the coin is caught directly in a hand, preventing it from bouncing. Additionally, the data suggests that when a penny is spun, it will land on tails approximately 80% of the time, likely due to the heavier side (the head) favoring downward momentum. However, I'm a bit doubtful about this; I tested it 20 times and achieved 11 heads and 9 tails. The odds of getting 9 or fewer tails in 20 spins, given an 80% chance, is roughly 1 in 1775.
Dear Expert, can you clarify why the cancellation system system isn't effective? (I am referring to the method known by various names, where you wager based on a range of numbers and cancel them out upon winning, etc.) It appears that just winning 1/3 and two of your stakes should lead to a profit. In roulette, your odds of winning stand at nearly 45%. Therefore, it seems logical that you would come out ahead in the long run, yet this often isn't the case. Why could that be?
As with most betting systems the cancellation system This method typically results in successful sessions but can also lead to sporadic significant losses. When this cancellation method experiences losses, the consequences can be devastating. During the periods where it feels like you are losing continuously, the stakes accumulate rapidly, which can quickly drain your finances if luck isn’t on your side.
In Yahtzee, if only the Yahtzee itself remains on the scorecard, what are the chances of achieving it?
The table below illustrates the probabilities of completing a Yahtzee on the final roll, based on the number of extra dice required.
Last Roll Yahtzee Probabilities
Needed | Probability of Success |
0 | 1 |
1 | 0.166667 |
2 | 0.027778 |
3 | 0.00463 |
4 | 0.000772 |
The next table outlines the chances of improvement. The left-hand column indicates how many dice you need before each roll, while the top row reveals how many are required after the roll. The body of the table presents the probability of achieving varying levels of improvement.
Probabilities of Improvement
Need Before Roll | 0 | 1 | 2 | 3 | 4 | Total |
0 | 1 | 0 | 0 | 0 | 0 | 1 |
1 | 0.166667 | 0.833333 | 0 | 0 | 0 | 1 |
2 | 0.027778 | 0.277778 | 0.694444 | 0 | 0 | 1 |
3 | 0.00463 | 0.069444 | 0.37037 | 0.555556 | 0 | 1 |
4 | 0.000772 | 0.01929 | 0.192901 | 0.694444 | 0.092593 | 1 |
Following that is a table that shows the likelihood on the first roll when needing between 0 to 4 additional dice to form a Yahtzee.
First Roll Yahtzee Probabilities
Needed | Probability |
0 | 0.000772 |
1 | 0.019290 |
2 | 0.192901 |
3 | 0.694444 |
4 | 0.092593 |
This next table presents the chances of enhancement and ultimately succeeding, depending on how many dice you need after your initial roll. For instance, if a player requires 3 additional dice to achieve a Yahtzee, the likelihood of reducing this to needing 2 after the second roll and then making the Yahtzee on the third roll is 0.010288066.
Probabilities of achieving a Yahtzee following the initial roll, based on the required number before and after the second roll.
Need Before Roll | 0 | 1 | 2 | 3 | 4 | Total |
0 | 1 | 0 | 0 | 0 | 0 | 1 |
1 | 0.166667 | 0.138889 | 0 | 0 | 0 | 0.305556 |
2 | 0.027778 | 0.046296 | 0.01929 | 0 | 0 | 0.093364 |
3 | 0.00463 | 0.011574 | 0.010288 | 0.002572 | 0 | 0.029064 |
4 | 0.000772 | 0.003215 | 0.005358 | 0.003215 | 0.000071 | 0.012631 |
To determine the final result, use the dot product from the count needed after the first roll from the previous table and the chances of eventual success from the final column of the preceding table. This results in 0.092593*0.012631 + 0.694444*0.029064 + 0.192901*0.093364 + 0.019290*0.305556 + 0.000772*1 = 4.6028643%. To verify, I simulated 100,000,000 games, achieving a simulated probability of 4.60562%.
I comprehend the functions of random number generators, virtual reel stops, and physical reel stops. However, what puzzles me, and what I cannot find answers for anywhere, is how the game establishes what the payout will be for the chosen symbols. For instance, in an IGT Red, White, and Blue game identified as number SS4335, the top jackpot—which consists of the Red, White, and Blue Sevens—corresponds to virtual reel positions 044, 043, 044, and physical reel stops 08, 08, 08, respectively. Each of the three reels features seven symbols: Red Seven, White Seven, Blue Seven, Red Bars, White Bars, Blue Bars, and Blanks. This amounts to 343 possible symbol combinations. I understand that the SS chip does not include a table with all possible outcomes and payouts. It must be indexed in some way. How does the machine ascertain that reel stops 08, 08, 08 correspond to the Red, White, and Blue Sevens, and how is the payout determined? I would appreciate any insights you might have, or if you could point me to relevant articles or books.
There exists a 'lookup' table that connects different random numbers to specific stops on the reels. However, I was uncertain how they transition from that stage to actually determining the player’s payout. I decided to consult a former mathematician in the slot machine industry, who wished to remain anonymous. He explained, \"Your initial assumption is correct. The position on each reel is randomly picked through the RNG. The code then checks the symbols across each activated payline to uncover winning combinations. This method is also applicable for scatter payouts. All major video slot manufacturers utilize this approach. You can think of the algorithm as a large series of if-then statements, but actual implementation may be even more sophisticated.\" I hope this information is useful.
P.S. Following the publication of this column, I received another email about this topic. It's somewhat lengthy, and I am providing you with it. this link .
Firstly, thank you for your fantastic website. Is there really no benefit to card counting if it’s a single deck game that gets reshuffled after each hand?
Thank you for the compliment! There is still some benefit, particularly in a full table context. However, under standard single-deck rules (like the dealer hitting on soft 17 and no doubling after splits), I don't believe the advantage is substantial enough to overcome the 0.19% house edge.
What are the chances of dealing four aces in a game of four-card stud?
1/combin(52,4) = 1 in 270725.
Dear Expert, could you explain how the house edge for place bets in craps is calculated? For example, how is the nine to five payout on a four/ten place bet related to a 6.67% house edge when the real odds are two to one? No matter how I approach this, I can’t seem to reach that 6.67% figure. It’s really perplexing me, and I would deeply appreciate a detailed explanation.
I like to compute the house percentage as 1-(probability of winning * payout - probability of losing). In this case, it would be 1-((1/3)*1.8 - (2/3)) = 6.67%. Alternatively, if you're familiar with both the fair payout and the actual payout, a straightforward formula for calculating the house edge is (f-a)/(f+1), with f representing the fair payout and a denoting the actual payout. Therefore, in this instance, (2-1.8)/(2+1) = 0.2/3 = 6.67%.
If you were wagering $50 per game, which would you opt for between these two video poker options (assuming identical payout structures and that you stake the maximum of 5 coins on every round): a single-play at $10 or a ten-play at $1 per hand? Thank you for your time and thoughtfulness.
Statistically, both options yield the same expected return. However, I'd prefer the 10-play version, as it tends to have lower variance and I find it more enjoyable.
Thanks for maintaining such a wonderful website. You recently commented that the average lifespan of a craps shooter is around 8.5 throws. I typically place the pass line bet with full odds and follow it with come bets, also with full odds. Given the long-term probabilities suggesting that the shooter might seven out within just three to four additional throws, wouldn't it be wise to cease making come bets after about four throws?
You're welcome! I appreciate your gratitude. Remember, the dice do not have memory. After four throws, there’s no increased likelihood of rolling a seven. It's quite possible to throw 1000 non-sevens and still be just as close or far from achieving a seven as you were on the first roll. There isn't a 'perfect' number of come bets; just play as many as you find enjoyable.
What are the odds of completing 15 spins on European roulette while covering eight numbers and not hitting any of them?
The chance of losing any single spin is 1-(8/37), which stands at 78.38%. Consequently, the probability of losing all 15 spins is .7838.15= 2.59%.