A single die is rolled, find the probability that the number is even or less than 6

1/1 chance, since 2,4,6 is even, and all numbers are less than 6 except 6, but since you said or, it doesn't matter because 6 is still even despite being not less than 6.

3/6 = even

5/6 = less than 6

3/6 X 5/6 = 15/36

P (even) + P (<6) - P (even and <6) = P (even or <6)

8/6 = 48/36

48/36 - 15/36 = 33/36 = 11/12

11/12 = 0.9167 = 91.67%