This app shows how the multiplication of two numbers can be reduced to the sum of two numbers. The first two lines represent two numbers in binary. The second three lines represent the expansion of the multiplication. The third two lines represent the reduced two numbers. You can put the results of the logic operations on the fourth two lines by clicking the digits. Logic operation for the expansion: 000->00, (001,010,100)->01, (011,101,110)->10, 111->11. Logic operation for the reduced sum: 00->00, (01,10)->01, 11->10. If you click the digits according to the logic operation, you will have the value for the multiplication of two numbers eventually.