How to multiply without knowing your tables ...

[Hugh-AR]

Being an ex Maths Teacher, I'm not sure if I would want my pupils to know about this. 'Make sure you know your tables' was my philosophy, and we had games and 'flash cards' (that had the answers on the back) to help them commit the answers to memory.

So how about this way of multiplying? The Chinese (or Japanese) way of doing multiplication.



Not sure I would want to multiply 987 x 678 by this method!

I suppose these days there is a better way than either of the above. Use a calculator!

Whilst on the subject of calculators, do you remember those first 'cheap' calculators we used to have? I remember once at a parents' evening being confronted by one parent who wanted to know why I was teaching his son wrong. He was referring to the answer to this sum ...

1 + 2 x 3 = ?

Well, the answer should be 7 .. but using one of those calculators it would give the answer 9. Which is why he was having a go at me. His calculator proved I was wrong. Which just goes to show how much faith we put in our electronic devices. Mathematically, in a mixed sum like this, the multiplication should be done before the addition.

So 1 + 2 x 3 = 1 + 6 = 7

If you wanted the answer to be 9 you would have to write it like this: (1 + 2) x 3 = ? And this answer would be 9 as you do the brackets first.

I am pleased to note that with the advance of electronics, the calculator on a Mobile does give the correct answer to 1 + 2 x 3 = ?. Try it and see.

Here endeth the Maths lesson.

Hugh

[Rev Tony Newnham]

Hi

BODMAS was the mnemonic we were taught to remember the order of mathematical processes. This sort of thing comes up on Facebook every so often - and it's amazing how many people get it wrong! (Brackets, "of", division, multiplication, addition, subtraction for those who were wondering!)

Back in the early '70's a colleague had one of the first - very basic - scientific calculators. That would tell you that the square root of 4 was 1.9999999!

Every Blessing
Tony