This circuit adds two digit . Give first digit by first four bits in upper 7 segment display and 2 digit by four bits at lowest last 7 segment display . Then starts play button and wait for some time . When upper display becomes zero see the result in lowest last diplay..
Initial value
upper display =15(F)
Loswest display = 9
So answere will be
Upper display = 0
Lower display = 24
(If sum is more than 9 then the ten's digit of result in lowest first display and one's digit in lowest last diplay)
(Dont give more than 9 in 2 diplay . I locked it so it will not work properly if 2 digit is more than 9)
Max sum =>> 15+9=24
