The probability of rolling at least one 4 plus the probability of rolling no 4s is 1.000.
It is easier to calculate the probability of rolling no 4s and subtracting that value from 1.000 to get the probability of rolling at least one 4 than it is to calculate the probability of rolling at leawst one 4 directly.
Probability of rolling no 4's: ---> the probability of rolling anything but a 4 is 5/6. This probability holds for each roll, so if you roll a die 7 times, the probability of never getting a 4 is: 5/6 x 5/6 x 5/6 x 5/6 x 5/6 x 5/6 x 5/6. Now, subtract this answer from 1.000 and the result is the probability of rolling at least one 4.
