A Rough Guide To Everyday Mental Calculation!

We all need to check a bill from time to time. The problem is, how do you do it when you're in a rush, when you're under pressure, and when you don't have a calculator handy? Actually, it's not at all difficult if you know what to look for. Here's how to do it... Example --------- Suppose you are ordering some building supplies and you want to check that the price is about right before you open your check book. You order posts at $. per post. These numbers can be approximated to posts at $ per post. Multiplying and is easy: the expected bill should be about $. Basically you just look at the figures and round them to the nearest convenient unit. (That's why we approximated $. to $). Example --------- Similarly for pieces of turf @ cents each, just find = cents = $. --- TIP -------------------------------------------------- When multiplying numbers ending in zeros e.g. x = : you always end up with the number of zeros added. So x , = ,, ( zeros) --- TIP -------------------------------------------------- Example --------- If there are more items in the bill you can still get a rough answer: planks @ $. each, joists @ $. each. Nails: $ Get = for the planks, and = for the joists. The nails are $, let's say $. So the rough total is: + + = $ Now who needs a calculator? --------------------------------------------------------- Excerpt from 'Fun With Figures Volume '. Discover how to perform everyday calculations the easy way - without having to rely on your electronic friend!. ---------------------------------------------------------