I studied the riddle for close to 30minute befor I could finally get it right..mhen e no easy because u ve to tink! Oya now make person help us out

kabnafs:
I studied the riddle for close to 30minute befor I could finally get it right..mhen e no easy because u ve to tink! Oya now make person help us out

Ur spent column is totally wrong, it should have been- 20,35,41,50.

Hehehehe.. Clever but it's quite obvious.
The table above does not represent the true state of the transaction na - albeit logically.

You are just adding the remainder of your cash at hand anytime a transaction occurs(demand is met).

The right calculation is adding all expenditure and equating it to total amount you had on you before buying anything:

total amount = exp1 + exp2 + exp3 + ... + remainder(if any).

What you did up there is like getting the total numbers of remainders when converting a number to base 2, then multiplying it by 2 thinking it will equate(everytime) to the original number being converted.