Working out mental arithmetic quickly...

Working out mental arithmetic quickly By: Dannyboy [13-January-09 11:19PM] 95 posts
If you need to work out a sum quickly, just round it up to get a rough answer. For numbers 1,2,3 round down, for 4, 5, 6 keep to 5 and above 6 round to 0. So if you have to do 48 x 52 for instance just treat this as 50 x 50 which is obviously 2,500. The actual answer is 2,496 so we're very close there with that easy estimate.

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