Write down the starting number and work card by card - each intermediate result underneath.
For a repeat card you really do calculate several times: "+2, three times" is +2, then +2, then +2 again.
If a card is hidden and the result is known, try out one number after another to see which fits.
In a duel two programs start on the same number: work out both and check off who lands higher - a small card with a repeat sometimes beats a big one.
Examples
Example
Example: duel
For parents
What does this exercise practice?
The calculation program introduces the loop: one command carried out several times. That is the basic idea behind all programming.
Common pitfalls
The repeat card often gets calculated only once. It helps to write the repeats underneath each other so none gets lost.
How to practice at home
Write your own program on slips of paper and let someone work it out. Ada Lovelace wrote down the first program of this kind over 150 years ago.