Which letter comes next in the series: S, M, H, D, W, M?
Y
Seconds, Minutes, Hours, Days, Weeks, Months, Years
Why this works
This riddle plays on the concept of time intervals, where each letter represents a unit of time. The series starts with "S" for Seconds, followed by "M" for Minutes, "H" for Hours, "D" for Days, "W" for Weeks, and "M" for Months. The next logical unit of time is Years, which corresponds to the letter "Y." So, the answer is "Y," as it continues the pattern of measuring time!