Add between 10% to 20% random to numbers in cloumn F

[SamT]

The result will be between 10.00000000000% and 20.99999999999% increase

Option Explicit

Sub AddToF()
Dim FArr
Dim i As Long

FArr = Intersect(Range("F1").CurrentRegion, Range("F:F")).Value

For i = 1 To UBound(FArr)
    If IsNumeric(FArr(i, 1)) Then _
        FArr(i, 1) = FArr(i, 1) * 1 + (Int((20 - 10 + 1) * Rnd + 10) / 100)
Next i

Range("F1").Resize(UBound(FArr, 1)) = FArr
End Sub

Example Returns, as percent additions:

10.999999940395400%
14.000000059604600%
18.000000715255700%
14.000000059604600%
15.999999642372100%
18.000000715255700%
17.000000178813900%
11.999999731779100%
15.000000596046400%
18.999999761581400%
11.999999731779100%
15.999999642372100%
15.000000596046400%
12.999999523162800%
20.000000298023200%
10.999999940395400%
17.000000178813900%
15.999999642372100%
17.000000178813900%
14.000000059604600%
12.999999523162800%
14.000000059604600%
10.000000149011600%