We have now published the second in our series of sets of mental arithmetic questions, suitable for Year 6 (10/11 yrs old). This week we are looking in particular at doubling, products and multiplying fractions by ten. Being able to double numbers is a very powerful mental strategy and can really speed up mental calculations. It is always interesting to ask children how they have gone about doubling a number as there are several different techniques that can be used. For example: double 19 can be done by: 1. actually knowing it off by heart 2. doubling 20 and subtracting 2 3. doubling 10 (20) then doubling 9 (18) and adding the results 4. doubling 9 (18) then doubling 10 (20) and adding the results. Some of the questions ask for the product of two numbers. It is a common mistake to add the numbers, but to reach the correct answer the numbers should be multiplied. Finally there are a couple of questions on multiplying decimals by 10. For example: 0.7 x 10. Watch out for the incorrect answer of 0.70 if children have been told to 'add a nought' when multiplying by 10. For younger children we have also published our second week of mental arithmetic questions for Years 4 and 5.