To determine the number of ways to pay a bill of 107 Misos using denominations of 1 Miso, 10 Misos, and 50 Misos, we use a combinatorial approach. Let's denote:
The equation to satisfy is:
x + 10y + 50z = 107
We need to find all possible non-negative integer solutions to this equation. We will consider the possible values of z (number of 50 Miso coins) first:
Hence, the total number of solutions is 1 (from 50 Miso = 100) + 6 (from 50 Miso = 50) + 11 (from no 50 Misos), which gives us a total of 17 ways to pay the bill of 107 Misos.
For any natural number $k$, let $a_k = 3^k$. The smallest natural number $m$ for which \[ (a_1)^1 \times (a_2)^2 \times \dots \times (a_{20})^{20} \;<\; a_{21} \times a_{22} \times \dots \times a_{20+m} \] is: