Egyptian multiplication: Under column headings , put as the first row of the table, then double each row to get the next row, continuing down as long as the numbers in the first column are less than or equal to . Now strike out (here shown in gray) enough of the rows so that the remaining first-column numbers add up to . (There is only one way to do this, as you can easily see: adding the left column from the bottom to the top, but throwing away any entries that would make the sum too big.) Now add the numbers remaining in the second column. The answer found will be .