Thetechnique for Dividing any number by 9 mentally is simply to reduce a complex divisionto a very simple addition. The technique can be applied from both ends i.e. from right-most digit or from left-most digit. Dividingby 9 into a mixed number from right-most digit uses the Divisibility Rules for9:1.     First, add all the digitstogether and divide by 9, keeping in mind the whole number and the remainder.2.     Write the remainder over 9, thisis the fraction part of the answer. (Make sure the fraction is in simplestform.)3.     Add a...