don steward
mathematics teaching 10 ~ 16

Tuesday, 11 January 2011

order of calculating

what is quite tricky to appreciate with bidmas or bodmas or pemdas is that there is no preference for division over multiplication or addition over subtraction (so it should really be b i d/m a/s)

Matt Dunbar (Trinity Maths) proposes using a trapezium picture:

in a similar vein (on the NCETM site - not sure whose idea it was)

when there is any ambiguity you follow a left to right procedure

using all of the digits 1 to 9, once only, can students see how the numbers at the ends are created?

in newspaper versions, these puzzles do not follow the bidmas rules

these puzzles do follow the bidmas rules
you use 1 to 9 once only to complete the puzzles

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