Can someone please explain to me the benefits of doing multiplication horizontally not vertically?

[superfluouscurves]

I'm a maths dunce and I am currently helping my dd (aged 9) revise for her end of term maths test - poor thing

Why do they teach multiplication horizontally nowadays? It's so much harder to keep the decimal points in the right place isn't it? What am I missing?

Try these

www.mathsisfun.com/multiplying-decimals.html
www.math.com/school/subject1/lessons/S1U1L5GL.html

I just accidentally replied to this on another thread!

Do you mean the method like this:...
14 x 5 = 10 x 5 + 4 x 5 = 50 + 20 = 70

It's much easier for children to understand the value of the digits this way, and it helps with mental calculation skills too.

Hi SC!
Teaching multiplication horizontally is on the Maths programme I have to teach too (as in, ellesabe's method above). To be honest, I find that some children really struggle with it, and I just reassure them that if they can do the vertical method then they shouldn't fret too much about it. I think it is just seeing all those numbers and symbols in the sentence together, that throws some children off. That and the little blank boxes, like usually the 4 in the above sum will be a little blank box.
If you strike out all the x5 in the above Maths sentence you get 14=10+? which they can easily figure out then that 4 is the missing number.
Hope that helps, I think I made it a bit muddly. Oh dear.

But it is good for mental calculation skills, especially as the children move on to multiplying larger numbers eg. 8 x 16 = well that's 8x10 plus 8x6 etc.

However....we don't teach multiplying horizontally with decimals. That would be quite tricky, especially for 9 year-olds. I would just use the vertical method for that....

Is that the Grid Method? It's brilliant in my mind, or maybe just for me. Accurate results with lower effort that really breaks down how the operation makes the sum appear.

I found the other way (like long division) is very black box. You follow the formula but you don't really understand why it gets the right answer.

Also, it is easier to visualise this method on a numberline, which many children are familiar with.

P.S. I'm impressed that your 9yo is multiplying decimals! She must be very bright :)

Thanks for your replies everyone - much appreciated!

She actually finds maths quite a challenge Ellesababe, it's definitely not her strongest subject. Sorry - I'm probably not explaining it very well - I meant that surely it would be easy to keep to the right decimal places... if that makes sense ...

To take an easy example, she is doing this sort of thing:

          9000        1200       60         3

3421 x3 (3000x3)+ (400x3)+ (20x3)+(1x3) = 10,263

It's fine when she is just multiplying by single numbers, but gets a bit confused thereafter, eg:

5 231 410= (5 X 1 000 000) + (2 X 100 000) + (3 X 10 000) + (1 X 1000) + ( 4 X 100) + 10

and

doing this ... 176 x 27 ! She can do it easily my old-fashioned way (vertically) but gets stuck when she is doing it horizontally (always seems to get one figure wrong, particularly when she is "carrying" a number (if that's still the correct term nowadays!)

As Castlelough says, t is quite straightforward when you delve in to it - but looks a bit offputting when you first see it.

Is that the grid method LLjkk? Not sure?!!

Thanks for those links Learnandsay - will investigate!

Castlelough and Ellesababe yes I can see it could help with mental calculation skills ... I'm afraid that is where I go fuzzy though - have to write it down or my brain explodes

Really trying not to pass on my maths blindness/negativity on to her though!!

The grid method would reeeally help her with the 2digx2dig ones! I can't really explain it though as it's quite visual.

Hang on...

YouTube tutorial here

I love the grid method - it really works.
But in the new maths curriculum it has no place. Everything is going back to standard written methods.

Sorry - meant to say the formatting on the first sum didn't position itself correctly on the first sum once I had posted it

Thanks for grid method link Ellesababe - really kind of you
Strangely, she does something similar for long division, but not multiplication

Pennygallops we are abroad so national curric. does not apply in this instance. Will try grid method with her - thanks!