A clock strikes once at $1:00$ o' clock and twice at $2:00$ o' clock, thrice at $3:00$ o' clock. so on. respectively. How many total strikes per day?

Question

Question: A clock strikes once at $1:00$ o' clock and twice at $2:00$ o' clock, thrice at $3:00$ o' clock. so on. respectively. How many total strikes per day?

Solution:

$$ 1+2+3+3.........= 12 = \frac{12(13)}{2} $$ $$=78 \times 2 $$ $$= 156 \space (Answer)$$

My doubt, how can a clock hits "once at $1:00$ o' clock" if $1:00$ o' clock happens twice at a day i.e $1$ AM and $1$ PM?

Answer 1

Note that the total strikes per day are

$$(1+2+3+...+12)+(1+2+3+...+12)=2(1+2+3+...+12)$$