A clock strikes once at 1 o'clock, twice at 2 o'clock and thrice at 3 o'clock, and so on. How many times will it strike in 6 hours?
1
21
2
58
3
78
4
41
A clock strikes once at 1 o'clock, twice at 2 o'clock and thrice at 3 o'clock, and so on. How many times will it strike in 6 hours?