--description--

For a positive integer $n$, define $f(n)$ as the least positive multiple of $n$ that, written in base 10, uses only digits $≤ 2$.

Thus $f(2) = 2$, $f(3) = 12$, $f(7) = 21$, $f(42) = 210$, $f(89) = 1\,121\,222$.

Also, $\displaystyle\sum_{n = 1}^{100} \frac{f(n)}{n} = 11\,363\,107$.

Find $\displaystyle\sum_{n = 1}^{10\,000} \frac{f(n)}{n}$.

--hints--

multiplesWithSmallDigits() should return 1111981904675169.

assert.strictEqual(multiplesWithSmallDigits(), 1111981904675169);

--seed--

--seed-contents--

function multiplesWithSmallDigits() {

  return true;
}

multiplesWithSmallDigits();

--solutions--

// solution required