What formula did you use to return the customer?
=VLOOKUP(A7,A1:C4,2,FALSE)
What formula did you use to return the Invoice value?
=VLOOKUP(A7,A1:C4,3,FALSE)
What would happen your formula if you entered a new column of data between the invoice number and the Customer in the lookup table?
if you entered a new column the vlookup would no longer work because the columns move so the column index number used in the formulas would no longer be correct
Nice work @dernan, you got all of this correct. There is actually a LOOKUP skills test available free on the website if you would like to try it out http://theexcelclub.com/excel-skills-testing/