<pre class="shiki github-dark shaku"><code>/** * @param {number} n - integer * @returns {string} */const evaluateNumberString = (numberExp) =&gt; { if (numberExp.length === 1){ return '1' + numberExp[0] } let prevNumber = numberExp[0]; let stringExpr = ''; let currCount = 1; for (let i = 1; i &lt; numberExp.length; i++){ if(prevNumber !== numberExp[i]){ stringExpr = stringExpr + `${currCount}${prevNumber}`; prevNumber = numberExp[i]; currCount = 1; } else { currCount++; } } stringExpr = stringExpr + `${currCount}${numberExp[numberExp.length -1]}` return stringExpr}function getNthNum(n) { if (n == 1){ return '1' } let numberEval = '1' for (let i = 1; i &lt; n; i++){ numberEval = evaluateNumberString(numberEval) } return numberEval}</code></pre>