Challenge 1: A Basic Exact-Match VLOOKUP — Solution Walkthrough

Table: A1:B5 = SKU-100/9.99, SKU-200/14.50, SKU-300/22.00, SKU-400/7.25

Formula:
  =VLOOKUP("SKU-300", A1:B5, 2, FALSE)

Result: 22.00

Walkthrough:
  1. VLOOKUP searches down column A (the first column of A1:B5) for
     an exact match to "SKU-300".
  2. It finds "SKU-300" in the 3rd row of the table.
  3. Argument 3 says "return the value from the 2nd column of the
     table" — that's column B, same row — which holds 22.00.
  4. FALSE told VLOOKUP to require an exact match rather than guess
     an approximate one, which is why it can correctly land on
     "SKU-300" specifically rather than the closest alphabetical
     neighbour.

What happens if FALSE is left out on unsorted data:

Leaving out the 4th argument (or using TRUE) switches VLOOKUP into
approximate-match mode, which explicitly ASSUMES the lookup column is
sorted in ascending order. If the codes in column A are not actually
sorted that way, VLOOKUP's internal search logic (which relies on
that sorted assumption to work correctly) can land on completely the
wrong row and return an unrelated price — with no error message at
all, since approximate match mode is specifically designed to always
return something rather than fail. This is exactly the "confidently
wrong result" risk this chapter's tip box warns about.

Notes:
- This is why the safe default is to always type FALSE (or 0)
  explicitly, every time, rather than relying on remembering that
  the data happens to be sorted correctly today — a later reorder or
  a new row inserted out of order would silently break an
  approximate-match VLOOKUP that used to work.