Count the gray blocks and type the number. If you get it correct, the happy face will smile. It is easier
if you know about the tens place and ones place. Count the columns with all gray blocks for the tens place, and the number of gray blocks in the last column
for the ones place. For example, 2 gray columns and 3 gray blocks in the last column is 2 tens and 3 ones, or 23.
Press 'Do it again' or the ENTER (or RETURN) key to try it again.