Long multiplication

Electronic calculators are really amazing, BUT they come at a cost – students can simply forget how to do the most basic things in maths – like long multiplication. The non-calculator GCSE exam was introduced to remedy this situation, and in recent years there have been several questions on non-calculator papers that test this basic skill of long multiplication. The marks are given not just for the correct answer but, more importantly, for the correct working out. Let’s suppose you are asked to work out this….
…well, the first thing to cause panic is the fact that one of these numbers is a decimal. Don’t worry, if you see a decimal number IGNORE THE DECIMAL POINT and write the question like this….
… now this looks a bit simpler to handle. Yes, there will be a decimal point in the answer but I will show you how to find exactly where to put it after we’ve finished the long multiplication.
We have multiplied every digit in the top number by the UNITS digit (the 5) in the bottom number to give the answer 3185. We now must multiply every digit in the top number by the TENS digit (the 4) in the bottom number. But we must record our answers startingin the TENS column. So to avoid writing an answer in the UNITS column a ZERO is placed in the UNITS column before we start, like this….