Weird Calculator Puzzles

You own a weird calculator with only 4 buttons, which perform the following 4 operations:  ×3  +7  -11  ÷2.

Your challenge is increment the numbers below by pushing only a certain number of buttons on the calculator. For example, 1 → 2 with 3 buttons has solution:  +7  ÷2  ÷2.

Each puzzle below has a unique solution. All puzzles copyright Erich Friedman, 2009.


1. 5 → 6 with 2 buttons 2. 6 → 7 with 2 buttons 3. 12 → 13 with 2 buttons

4. 13 → 14 with 3 buttons 5. 19 → 20 with 3 buttons 6. 26 → 27 with 3 buttons

7. 4 → 5 with 4 buttons 8. 30 → 31 with 4 buttons 9. 47 → 48 with 4 buttons

10. 61 → 62 with 5 buttons 11. 69 → 70 with 5 buttons 12. 87 → 88 with 5 buttons

13. 42 → 43 with 6 buttons 14. 60 → 61 with 6 buttons 15. 75 → 76 with 6 buttons

16. 117 → 118 with 7 buttons 17. 127 → 128 with 7 buttons 18. 139 → 140 with 7 buttons

The answers are here.

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