Selecting Ten Random Numbers

What about using VBA:

Sub UniqueRandomNumbers()
'Original idea was from Wellsr.com
'I modified it to play with Lotto numbers, (didn't do me any good)
'but for this exercise, maybe it could work

Dim lowLimit As Long, highLimit As Long, numCount As Long
Dim dict As Object, arr() As Variant, i As Long, j As Long, temp As Variant
Dim r As Long

' Sheet Layout:
' A3 = Lower limit
' B3 = Upper limit
' C3 = Number of randoms
' E3 = Random number output

lowLimit = Range("A3").Value
highLimit = Range("B3").Value
numCount = Range("C3").Value

If numCount > (highLimit - lowLimit + 1) Then
MsgBox "Not enough unique numbers in range!", vbExclamation
Exit Sub
End If

Set dict = CreateObject("Scripting.Dictionary")

' Seed random number generator with system clock
Randomize

' Generate unique random numbers
Do While dict.Count < numCount
r = Int((highLimit - lowLimit + 1) * Rnd + lowLimit)
dict(r) = 1
Loop

' Transfer dictionary keys to array
arr = dict.Keys

' Sort ascending
For i = LBound(arr) To UBound(arr) - 1
For j = i + 1 To UBound(arr)
If arr(i) > arr(j) Then
temp = arr(i)
arr(i) = arr(j)
arr(j) = temp
End If
Next j
Next i

' Clear old results
Range("E3").Resize(1000, 1).ClearContents

' Output of unique randoms
Range("E3").Resize(numCount, 1).Value = Application.Transpose(arr)

End Sub

I never liked using Excel's random number generators. Two reasons:

1) The functions are computationally intensive, making them very slow if you need a lot of random numbers, such as for a Monte Carlo simulation.

2) They recalculate with every refresh, which makes debugging and verification difficult.

Instead, I like to copy and paste values from a table called "A Million Random Digits with 100,000 Normal Deviates." It was published by the Rand Corporation in the 1955. It's available online for free.

This table has been thoroughly vetted. Just pick a random spot and copy as many values as needed. You will get random numbers that won't change with every recalculation.

Allen's comment about the second formula is a bit mystifying. Using the RAND() function may well give 15 digits of precision, but by the time the result has been multiplied by 150 and then truncated by the INT() function to just 3 significant digits, you have just as much chance of returning duplicates as the previous formula.

If truly random numbers need to be generated, Excel is probably not the generator of choice.
Online random number generators are probably better, e.g. random.org/integers has a simple interface that serves this purpose extremely well and has an API that could be used (by someone more experienced than I) to produce the desired output automatically.

But even truly random numbers may well still produce duplicates.