Challenge 2: A Fully-Qualified For Each Price Increase — Solution Walkthrough

Option Explicit

Sub IncreasePrices()
    Dim cell As Range
    For Each cell In Worksheets("Prices").Range("B2:B20")
        cell.Value = cell.Value * 1.1
    Next cell
End Sub

WHY THIS WORKS AS AN ANSWER
------------------------------
Dim cell As Range declares a variable that will represent, one at a
time, each individual cell the loop visits. For Each cell In
Worksheets("Prices").Range("B2:B20") loops directly over every one of
the 19 cells in that range — no counter variable needed, since
For Each hands you each cell object in turn automatically.

cell.Value = cell.Value * 1.1 reads the cell's own CURRENT value,
multiplies it by 1.1, and writes the result straight back into that
same cell — a 10% increase applied in place.

The key requirement this exercise specifically tests — fully
qualifying every reference — is satisfied by writing
Worksheets("Prices").Range("B2:B20") explicitly, rather than just
Range("B2:B20") on its own. Because the sheet name is stated directly
in the loop's own range expression, every cell object the loop
produces already belongs to the Prices worksheet specifically; there
is no unqualified Range or Cells call anywhere in this procedure that
could silently default to whatever sheet happens to be active when it
runs.

Notes:
- This is the direct antidote to this chapter's own warning box: had
  the loop instead read "For Each cell In Range("B2:B20")" (with no
  worksheet named), the macro would still run without any error, but
  would silently increase prices on whichever sheet the user happened
  to have open at the time — not necessarily "Prices" at all.