Ha ha, I see what the landlord means, that is, I want to double the basketball, so as to ensure that as long as the basketball is opened, all the previous investment can be recovered without loss.

What the landlord means is to ask how much the first phase of 100 costs.

Tell the landlord that this is an amazing number and double it by the landlord's method. By the 100 issue, you need to bet 5.9 * 10 2 1 lottery tickets in the current period, and at this time, the total * * has invested 3 * 10 22 yuan (1 100 million is 10).

In fact, by the 30th issue, the betting multiple of the current period has reached 654.38+0.74 million times, and the money already invested has reached 876.5438+0 million.

The exact formula is a bit complicated. I worked it out with a program. However, I can tell the landlord a simple estimation formula. The landlord can use (5/3) (n-2) to estimate the betting multiple of the current period. Duration.

The estimation formula is as follows: the cost of buying a two-color ball is 2 yuan, the blue ball wins the prize in 5 yuan, and the profit is 3 yuan.

Assuming that betting X times in M period is only to ensure the income (that is, betting X times, if winning the prize, the investment in the previous m- 1 period can be recovered), then the betting multiple of m+ 1 period should be X+[2x/3], [] stands for the nearest integer, and this formula means the previous m- 1 period.

The reason why n-2 is used instead of N in the index is because the third period began to double.

Hehe, well, the landlord's problem needs to be discussed.