title: How to distinguish if sumproduct needs to be inserted with CSE or not?
body: <p>I sometimes use the inherent array functionality of sumproduct to avoid havingt to enter formulas with Control + Shift + Enter. But it isn't always working. For example</p>
  <pre><code>=SUMPRODUCT((LEN(B2:F2)-LEN(SUBSTITUTE(B2:F2,M$2:M$10,&quot;&quot;)))*N$2:N$10)
  </code></pre>
  <p>would work, while</p>
  <pre><code>=SUMPRODUCT(--IF(ISNUMBER(N6:N9),N6:N9))
  </code></pre>
  <p>would not.</p>
  <p>It isn't really obvious to me, why the first one gives correct results, while the second does not.</p>