Vivek lists all whole numbers from 1 to 12 whose Roman numeral uses exactly three symbols.
How many such numbers are there?

Writing each: 1=I, 2=II, 3=III, 4=IV, 5=V, 6=VI, 7=VII, 8=VIII, 9=IX, 10=X, 11=XI, 12=XII. The ones with exactly three symbols are III (3), VII (7) and XII (12). That is 3 numbers (VIII has four symbols).