Day 7 – BODMAS, PEDMAS and the answer to Day 1 – Maths

Thanks to my followers for taking part in my Day 1 Maths problem.

Firstly, the answer is 5, using the usual BODMAS / PEDMAS rules of maths.

During one of my first lessons at high school, my maths teacher asked us all to get our calculators out and try out this calculation:

1 + 2 x 3

Anyone with a calculator showing 9 had to put their calculators away, and purchase a brand new Casio calculator that followed BODMAS rules. This was at the hefty cost of £15 at the time (ok, it was close on 20 years ago), which I’m sure was worth the money as it showed the ‘correct’ answer of 7.

BODMAS / PEDMAS

For those who don’t know or have forgotten, maths follows strict rules of calculation. Known as BODMAS (or PEDMAS in some regions), the order of calculation is:

B = Brackets (or Parentheses)
O = Orders (or Exponents / powers)
D = Division
M = Multiplication
A = Addition
S = Subtraction

Bod was quite a popular childrens program when I was growing up, so this was quite easy to remember – the cartoons are all on youtube! Using these rules our original calculation needs to be done as follows:

B: None here
O: None here
D: 4 ÷ 2 = 2
M: 2 x 2 = 4
A: 3 + 2 x 2 = 3 + 4 = 7
S: 3 + 2 x 2 – 4 ÷ 2 = 3 + 4 – 2 = 7 – 2 = 5

Brackets are used to clarify or indeed change the order of calculation, so:
(3 + 2) x 2 – (4 ÷ 2) = 5 x 2 – 2 = 8

For those who want a further challenge –

How many different answers can you get by adding brackets to the original calculation but keeping the order of numbers / operators the same?

I have shown you two –
3 + 2 x 2 – 4 ÷ 2 = 5
(3 + 2) x 2 – (4 ÷ 2) = 8

Don’t you just love maths!

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