title: Use of =lookup() - using multiple columns e.g. =LOOKUP(a1,$E$1:$F$24,$G$1:$G$24)
body: <p>I just found out how to lookup a date within a range of dates (source: <a href="https://www.mrexcel.com/forum/excel-questions/621562-vlookup-if-date-between-2-dates-table.html" rel="nofollow noreferrer">https://www.mrexcel.com/forum/excel-questions/621562-vlookup-if-date-between-2-dates-table.html</a>)</p>
  
  <p>Although, I cannot seem to find any documentation on how =lookup() searches both columns. Can someone please explain how it works?</p>
  
  <p>Please see below for the formula, and example data.</p>
  
  <p>Formula:</p>
  
  <pre><code>=LOOKUP(b1,$a$5:$b$7,$c$5:$c$7)
  </code></pre>
  
  <p>Example:</p>
  
  <pre><code>Lookup  9/10/2017
  Result  Week 2
  
  Week Start  Week End    Week Number
  27/09/2017  3/10/2017   Week 1
  4/10/2017   10/10/2017  Week 2
  11/10/2017  17/10/2017  Week 3
  </code></pre>