In not being able to do my 10 year olds math homework!

(147 Posts)
Livesforbedtime Wed 05-Mar-14 18:51:11

blush

I don't understand this.. She has to work out 23 x 22..

Now I'm not the sharpest pencil in the box, but I have a degree and a responsible job... So WHY when I worked it out as:

20 x 20 = 400
2 x 3 = 6

Answer = 406

But it's not is it? It's 506.. But I don't understand why confused

My poor 10 year old DD is bewildered.. And I cannot understand why I'm wrong yet I know I am!

I suspect it have a mind block... Yes that's it.. I'm not truly stupid hmm ok I might be..

It doesn't make sense! angry

welshnat Wed 05-Mar-14 18:52:52

It's 23 x 20 + 23 x 2 = 506

welshnat Wed 05-Mar-14 18:53:22

It is an easy mistake to make though. I had to think twice smile

DarlingGrace Wed 05-Mar-14 18:53:22

Because you dont work it out old school LMAO

23 X
22
460
_ 46_
506

Lovecat Wed 05-Mar-14 18:53:39

It's 23 lots of 22, though, so your way makes no sense at all...

Is that how the school have asked them to do it??

Cuxibamba Wed 05-Mar-14 18:53:48

Wouldn't you do 20x22= 440
3x22=66?

TheWomanWithTheMysteriousLump Wed 05-Mar-14 18:54:26

You have to multiply the two 20s by the 2 and the 3 as well.
20*20
+2*20
+3*20
+2*3
=506

Cuxibamba Wed 05-Mar-14 18:54:28

Then add them together.

startwig1982 Wed 05-Mar-14 18:55:00

It's because you need to do:
20 x 20
20 x 2
3 x 20
2 x 3
You must multiply all the bits together.
Most children learn by grid method where you split the numbers into tens and units, therefore having 4 sums that you add up at the end.

LIZS Wed 05-Mar-14 18:55:20

20x20= 400
20x2=40
3x22=66
total 506

Livesforbedtime Wed 05-Mar-14 18:57:22

Oh god so I am stupid?! blush

It's just made sense now. Honestly I was so adamant I was right! My poor DD is now more confused than when she started!

Must learn to just leave well alone!

Primrose123 Wed 05-Mar-14 19:01:14

Think of it more as

20 x 22 and 3 x 22

which would be

440 and 66 = 506

Using your method, you also have to do 20x2 and 3x20. Does that make sense?

Livesforbedtime Wed 05-Mar-14 19:01:54

Ohhh that makes much more sense!!

Logg1e Wed 05-Mar-14 19:04:25

If you can't do 23 lots of 22, can you do...
2 lots of 22?
4 lots of 22?
10 lots of 22?
20 lots of 22?
And so on.
Can you use these facts to get to 23 lots of 22?

I can't do my twins year 4 maths. My DD's year 7 maths is beyond me. I learnt Smile maths at my comp and it has a lot to answer for!!!

Ubik1 Wed 05-Mar-14 19:08:15

My DD aged 9 has now surpassed my levels of arithmetic , only DP with his superior Scottish education hmm can help her - although he told me the other day that he has 'forgotten all my trigonometry'

I did statistics as part if my degree and it all made sense to me but adding, subtractionabd long division? Nah.

Laurasmile Wed 05-Mar-14 19:14:39

Unsure of what multiplication method she'll have learnt at school - but the grid method for multiplication gets taught at secondary and helps avoid making that mistake - handy youtube tutorial

Ubik1 Wed 05-Mar-14 19:16:20

Oh we did Smile maths as well - basically you left school being able to draw nice pictures but no idea how to actually calculate anything. Can draw a great pie chart though. Never learnt my times tables either.

Livesforbedtime Wed 05-Mar-14 19:18:56

Oh see now this is more like it.. Feel much better now grin I too can do an almost bar chart.. It's a work of art really...

Livesforbedtime Wed 05-Mar-14 19:19:13

awesome

Ubik1 Wed 05-Mar-14 19:28:57

It was really important to choose nice complementary colours and colour in carefully. New felt tips made it extra special grin

soverylucky Wed 05-Mar-14 19:30:06

math?

BikeRunSki Wed 05-Mar-14 20:34:34

I did a Smile Maths, went on to do A level Maths and a Physics degree!

YABU to call it math though.

Livesforbedtime Wed 05-Mar-14 21:06:37

MathS hmm honestly you people that deliberately correct people constantly really bloody irritate me.

I didn't ask for a grammer/spell check and I really dislike the snidey 'ooh look what I found.. A mistake! grin

Do you guys have any idea how absolutely childlike and pedantic you come across to average normal people?

angry

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