An ATM (Automated Teller Machine) only provides Rp 20.000 and Rp 50.000. What kind of money multiplier which can be issued by the ATM? Prove your answer by induction. Note: Rp stands for Rupiah (the currency in Indonesia).
I have some trouble to clear this problem. Please help me. Regards. Notes that it doesn't mean that I don't provide you my attempt. Honestly, I have no idea where to start, the basis and induction steps can be done next.
It is clear that any amount which is not a multiple of Rp 10.000 cannot be provided, that the amount Rp 20.000 can be provided and that the amounts Rp 10.000 and 30.000 cannot be provided (in spite of the fact that 10.000 and 30.000 are multiples of 10.000).
Now, prove by indection that any multiple of Rp 10.000 starting from Rp 40.000 can be provided by the ATM.