Brush up your maths skills 33 not a problem if you need to write down long division. (Just be sure to get the decimal columns in the right place!) Remember, though, that each time you do this on a test it is taking up valu- able time. Let's look more closely at how mental arithmetic can help you work more quickly and efficiently. You are not going to need to work out that 12 12 144. But you are going to be faster at working out many simple calculations in your head if, upon seeing numbers such as 14,400, you are confident that: G G G this number is divisible by 12 (and hence know that this number must therefore be divisible by both 4 and 3); you can apply your multiplication table knowledge to such large numbers; you can work out many simple calculations without