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BODMAS
By Chris Gray on Friday, July 19, 2002 - 11:20 am:

Training to be a primary teacher and we are expected to teach the children BODMAS. Fine, however what I want to know is why that way round. There must have been a point when someone sat down and thought thats the right way to go about things and I want to know who. Even if its only in a vague 'the Egyptians were the first to sequence this way' sort of answer. There will be some child I teach who will ask why we do things this way and just telling them that 'we just do, now get on with it', is not good enough. So if anyone is out there who knows please drop me a line.

By John Grindall on Saturday, July 20, 2002 - 10:22 am:

I suppose when the first electronic calculators were made they had to choose some way of doing things for them, and BODMAS seemed a good one?

By Arun Iyer on Saturday, July 20, 2002 - 01:09 pm:

I had asked my teacher the same question and she replied....

"I think its because this system offers maximum flexibility"

I asked her what she meant by flexibility and she said...

"Arun,work out all the different systems you can think of and see if you come across any problem..."

so I went ahead and worked on some systems like BOSDAM...I saw that these systems created problems in my working,especially when I tried to apply these systems to solve quadratic equations.....

I still am not sure if my teacher is right but her point seems valid...

love arun

By Nicholas Dean on Wednesday, July 24, 2002 - 04:04 am:

Brackets first because parenthesised things are grouped together.
Of next because when people use that word ("of") it is short enough to sound as though it refers to only the next item --- you would have to utter any subsequent items very quickly to make the "of" sound as though it refers to the whole group, or pause after you utter "of" --- even so, this implies the group is bracketed.
That leaves DMAS...

By Ian Short on Friday, July 26, 2002 - 11:34 am:

Perhaps not a very helpful answer Chris (I do not know the historical origin), but you could always tell the children that it is a convention and it's certainly better that everyone sticks to the same convention rather than having different ones; for communication purposes.

You could equally have × meaning + and vice-versa and the only key problem would be that noone else would know what you're talking about!

Ian

By Emma McCaughan on Friday, July 26, 2002 - 12:43 pm:

Seeing the mention of calculators, I should point out that not all calculators use BODMAS - one nice way of introducing the need for a convention is to give out a mixture of scientific and basic calculators and get everyone to do the same sum!

By the way, I prefer BIDMAS, where I stands for Indices (powers). By the time they get to evaluating expressions, the most common error is on 3x2: many pupils instinctively evaluate (3x)2.