Year 5: Multiplying Decimals Knowing times tables off by heart is a crucial part of maths but it is by no means the only important aspect of understanding multiplication and being able to calculate mentally. A key concept is to understand what happens when numbers are multiplied by 10, 100 or 1000. Put at its most simple: When you multiply a number by 10 the digits move one place to the left. When you multiply a number by 100 the digits move two places to the left. When you multiply a number by 1000 the digits move three places to the left. A further step is to understand that multiplying by 100 is equivalent to multiplying by ten and again by ten. This is just as true when multiplying decimals as when multiplying whole numbers. So 5.56 multiplied by 10 is 55.6, with each digit moving one place to the left. Our latest set of worksheets for Year 5 covers multiplying decimals by 10, 100 and 1000. Remember, when dealing with multiplying by ten with decimals the much heard phrase ‘multiply by ten by adding a nought’ is entirely inappropriate. Go to Year 5 Multiplication