Working with Operators

Declaring variables gives you somewhere to store values. Operators are how you combine, compare, and test those values — which is really just how you express a business rule in code. "Is stock below reorder level?" is a comparison operator. "Reorder if stock is low AND the product is Electronics" is a logical operator.

Arithmetic Operators

Most of these behave exactly as you'd expect from a calculator, but VBA has two division operators that do genuinely different things:

Dim total As Double
total = 45 * 3      ' multiplication → 135
total = 100 / 3     ' division → 33.33...
total = 100 \ 3     ' integer division → 33 (drops remainder)
total = 100 Mod 3   ' remainder only → 1
total = 2 ^ 3       ' exponent → 8

The backslash (\) and Mod are the two that trip people up, because they look similar but answer opposite questions. 100 \ 3 answers "how many whole times does 3 go into 100?" — the answer is 33, and whatever's left over is thrown away. 100 Mod 3 answers the mirror-image question, "what's left over after 3 goes into 100 as many whole times as it can?" — the answer is 1. Put together, 33 groups of 3 plus a remainder of 1 equals 100 — that's not a coincidence, that's what the two operators are designed to split apart. This pairing is exactly how you'd calculate "how many full boxes of 3 can I pack, and how many units are left over for a partial box?" or check whether a row number is even (i Mod 2 = 0).

Comparison Operators

These return True or False:

44 > 30      ' True
44 = 44      ' True
"Office" = "office"   ' False — VBA's default string comparison IS case-sensitive
44 <> 30     ' True (not equal)

Logical Operators

These combine two or more comparisons into a single True/False result — exactly how a business rule with multiple conditions gets expressed:

If category = "Electronics" And stock < 30 Then
    ' triggers only if BOTH are true
End If
 
If category = "Office" Or category = "Electronics" Then
    ' triggers if EITHER is true
End If
 
If Not (stock < reorderLevel) Then
    ' triggers if stock is NOT below reorder level
End If

And requires every condition joined by it to be True before the whole expression is True — the first example only fires for Electronics products that are also genuinely low on stock, not for every low-stock product regardless of category. Or requires just one condition to be True, which is how you check membership in a small set of acceptable values. Not simply flips a True/False result to its opposite — it's often used, as in the third example, to express a rule as "NOT the bad condition" when that reads more naturally than restating the good condition directly.

String Concatenation

Joins text with & (not +, which VBA reserves for numbers):

Dim message As String
message = "Product: " & productName & " | Stock: " & currentStock
' Product: Wireless Mouse | Stock: 134

Notice currentStock is a number (134), not text, yet it concatenates into the string without any conversion step — VBA automatically converts a number to its text representation when you use & on it. That convenience is exactly why & is preferred over + for joining text: if you wrote "Stock: " + currentStock, VBA would try to interpret the whole expression as arithmetic and either throw an error or produce a confusing result, depending on context. & always means "join as text," with no ambiguity.

Task

1. Using the Monitor Arm's data (Price 89.99, Stock 18, Reorder Level 10), write an expression that checks whether stock is less than or equal to reorder level plus 10 — a "getting close" warning rather than a hard alert.
2. Build a concatenated message: "Monitor Arm is at 18 units (reorder at 10)" using variables, not hardcoded text.