1, open Excel, a new blank form in A1 write red ball, B1 write blue ball.
2, in A2 write =1+int (rand () *33), enter.
3, move the mouse to the lower right A2, so that the cursor into a black cross.
4, hold down the left mouse button, drag the mouse to A7, let go.
5, in B2 input =1+int (RAND () *16), enter.
6, the A1-a7 set to red, B1-B2 set to blue, centered.
7, the mouse clicks the blank cell, presses the DEL key, every time the number randomly changes once.