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Maths - what on earth is partitioning and how come I can't do it?

(8 Posts)
saltire Fri 28-Sep-07 08:06:35

DS1 has brought homework home, maths which he hadn't done. It's maths and its called partitioning. I think he's doing it wrong, but he insists he isn't.

Heres one of the example
In my money box I ahve £29.65. I earn £12.76 pocket money. How much do I have altogether?

Now I worked it out the way I always do and came up with£42.41.
DS insists thats wrong and it needs to worked out like this

2 9 6 5
+ 1 2 7 6, and then add each number to the one under it, by partitioning, adding a line between them.

Then I have to add
he keeps coming up with 3131, but I don't know what he's doing with the spare 1's, in 9+2 for example, it's 11, but he's only putting down 1, and I don't know where the extra 1 goes,a dn he says that is how he has been shown how to do it.
I've confused myself , and I'm sure he is wrong because how can they teach children thats the way to do maths if the answer is wrong?

tiredemma Fri 28-Sep-07 08:09:41

DS1 had this at school the other day- he explained it to me ( But can I remember it to explain to you?? Nope.)

sorry. maths is not my strong point.

Hallgerda Fri 28-Sep-07 08:18:30

Yes, you're right. He's left out the awkward little bits that you and I call carrying figures. And yes, they are still used in the new-fangled method, which works something like:

<Partition both summands into powers of 10, you know, units, tens, hundreds, thousands>

2965 + 1276 = 2000 + 900 + 60 + 5 +1000 + 200 + 70 + 6

<Group units, tens, hundreds, thousands etc. together to add them>

= (2000 + 1000) + (900 + 200) + (60 + 70) + (5 + 6)

= 3000 + 1100 + 130 + 11

<Oh dear, you can add hundreds together and end up with thousands. Just have to partition again then...>

= 3000 + 1000 + 100 + 100 + 30 + 10 + 1

<And another round of adding>

= 4000 + 200 + 40 + 1

= 4241

<At last!>

As you can see, it's really the method we know and love, just presented a bit differently.

saltire Fri 28-Sep-07 09:09:22

hmm. And that's the method they teach them.......why?
It looks bloody difficult to me, but then I got thrown out of maths

Creole Fri 28-Sep-07 09:45:00

I'll do it like this:

.11 = 5+ 6 = 11
1.30 = 6+7 = 13
11.00 = 9+2 = 11
30.00 = 2+1= 3

You still carry the 1 over though, maybe I'm wrong!

saltire Fri 28-Sep-07 15:17:08

But I still don't see the point of doing it that way. Why not stick to the way it's always been done.

Hallgerda Sat 29-Sep-07 21:40:23

It's really equivalent to the method we know and love, and is supposedly easier to understand. Undoubtedly easier to cock up though sad

So, yes, I wish schools stuck to good old-fashioned column addition too. Just wait till you see what they do to multiplication and division...

collision Sat 29-Sep-07 21:45:49

oh gawd! I have all this to come!!!

Why do they change things....I have just had a problem with handwriting.

DS1 is 5 and trying to join his name up but he cant!!

I thought he could as he was trying to join an 'a' to an 'x'. In my day you could do this as the x was more 'curly(!)' than straight but that has been changed now and it is definitely an X.

that maths looks very complicated but it looks like Hallgerda has it sorted! grin

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