Four cards lie at the front. At the end of the row is the card with the target number.
Exactly two cards add up to the target number.
Try the pairs one after another and circle the pair that fits.
Example: target 65, cards 24, 35, 46 and 41.
24 + 35 = 59, that is too little. 24 + 41 = 65, that fits.
So the 24 and the 41 belong together.
The marked cards show the solution.
Example
For parents
What does this exercise practice?
Look for pairs of numbers that make a target, trying systematically instead of at random.
Common pitfalls
Wild guessing takes a long time. Better to go in order: first all pairs with the first card, then with the second.
How to practice at home
Lay out four cards, name a target number and race to find the matching pair.
Related: Splitting Numbers, Secret Card