How to handle product of two or more digits crossing the limit of 15 digits in excel|VBA & Macros|Excel Forum|My Online Training Hub

Sub math()
Dim num As String
Range("c2:g21").ClearContents
a = Range("a2")
a2 = Range("a3")
Range("c1:g21").NumberFormat = "@"

b = Range("b2")
d = 1
For Count = 1 To b
c = a * a
Range("c" & d + 1).Value = WorksheetFunction.Rept(a, d)
Range("d" & d + 1).Value = "X"
Range("e" & d + 1).Value = WorksheetFunction.Rept(a2, d)
Range("f" & d + 1).Value = "="
num = WorksheetFunction.Product(Range("c" & d + 1).Value, Range("e" & d + 1).Value)
Range("g" & d + 1).Value = num
d = d + 1
Next Count
End Sub