Combination — adding
Handle the case where a big friend is not enough on its own.
Set 5 and add 6. Big friend says +6 = +10 − 4. So carry 1 to the left — but now you have to take 4 off a rod showing 5, and there are no 1-beads at the bar to take.
So the 4 comes off using a small friend: −4 = −5 + 1. Altogether: +6 = +10 − 5 + 1.
This is the only situation where one rod needs two techniques at once, and it happens only for +6, +7, +8 and +9.
Combination — adding
Used when the big-friend step cannot be taken off directly, so a small friend is needed as well.
- +9 = +10 − 5 + 4
- +8 = +10 − 5 + 3
- +7 = +10 − 5 + 2
- +6 = +10 − 5 + 1
Now you try
Fresh problems every time you open this page, built to need the technique above.
Finished
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