August 2026 Problem of the Month

Your strange new calculator has only four buttons on it.
Button A adds 11 to whatever is showing on the display.
Button B subtracts 7 from the number.
Button C multiplies it by 3.
Button D divides it by 2.

Now, with just these four buttons, you can change any whole number into any other whole number.

Can you determine how to change the first number in each pair below into the second one, using only those four buttons and doing it in the allotted number of calculations?
You may use each button more than once, and not every button will be used in every problem.



1. Change 50 to 51, pressing 5 times.
2. Change 9 to 90, pressing 5 times.
3. Change 0 to 111, pressing 6 times.
4. Change 101 to 0, pressing 6 times.
5. Change 19 to 91, pressing 6 times.