A clock strikes once at 1 o’clock, twice at 2 o’clock, … 12 times at 12 o’clock. How many times will it strike in a day?

Irza Afzad Arithmetic/ Basic Math, css, Full List, Mathematics

A. 78
B. 136
C. 156
D. 168

Solution:
Sum(1+2+…+12)=78 strikes in 12 hours
In 24 hours = 78 × 2 = 156
Answer: C