Take the two numbers that you want to multiply and write them down side by side. Double the one on the left and write that number beneath. Halve the one on the right and write that beneath the number just halved. ie
65.......86
130.....43
Keep doing this, doubling the one on the left, and halving the one on the right. If the number on the right is odd, like 43 above, put a * next to it, and when you halve it, forget about any fractional remainder. Keep doing this until the number on the right is 1 (which you'll also put a * beside, because it's odd). You end up with....
65............86
130..........43*
260..........21*
520..........10
1040..........5*
2080..........2
4160..........1*
Now add the numbers in the left hand column, but only the ones where there is a star on that line, so 130 + 260 + 1040 + 4160 = 5590, which is what you get when you multiply 65 by 86.
Ta da!
You have just, apparently, broke these number down into base two (binary), to do multiplication the different way.
