One of the logic problems in programming that most break the head of those who are starting are the problems with percentage calculation or interest.
It starts like this: Calculate 10% increase on a salary of $2,500.00
Depending on the student’s math background, percentage is learned in 4th/5th grade… some concepts need to be remembered. As the name says, 10% means that for every 100 of the value, you should subtract 10. The calculation is quite simple and can be done with a multiplication. For example: 10/100 * 2500, which results in 250. So far so good, but some students ask why sometimes we do 0.1 * 2500. Well, it’s just the way of representation that changes, because 10/100 is equivalent to 0.1, alias 100/1000 also and so on. But this is the easy part and after getting the notation right, things start working again.