To combine all four spins into a total probability that at least one win, you use the "at least one rule." First, find the probability that all of them will _fail_. Then, subtract it from one.

Code:

```
P(all) = (1 - 1/5000) * (1 - 1/4000) * (1 - 1/3000) * (1 - 1/2000)
P(at least one) = 1 - P(all)
P(at least one) = 1 - (0.9998 * 0.99975 * 0.999666 * 0.9995)
P(at least one) = 1 - 0.998717 = 0.00128 = 0.128%
```

For four spins of 1/1250, it's the same process, but a little more simplified.

Code:

```
P(fail) = 1 - 1/1250 = 1 - 0.0008 = 0.9992
P(at least one) = 1 - 0.9992^4 = 1 - 0.9976 = 0.0024 = 0.24%
```