# Talk

## Subtraction for Year 4

(11 Posts)
Mon 19-Jan-15 08:11:28

My DD is struggling with division of larger numbers. We did some homework to find differences between smaller and larger numbers and she is has been taught a formula, which she is a little confused about how it works. It is is different to how I have been taught, but honestly, I am so hopeless at doing the formula way (just do units, tens, hundreds in my head, and I am a bit rubbish at maths anyway, so do rely on a calculator) that I don't really get what she is trying to do.

She got herself in a bit of a muddle, and I have asked the teacher in her contact book to go through it with her again, and for me to have a copy of the way they are teaching it, so we can go through a few this week to make sure she is understanding it properly.

But, in the meantime, I feel stumped and a bit embarrassed that I didn't get yr4 homework while waiting for the formula to be shown to me, does anyone know what this might be?

It's the usual

451
396
_
_

but with like the 6 carried across and put in front of the 5, then a 5 added to the 1, or something. It worked for some her her sums, but the last one she got muddled and I couldn't help!

Thank you

Mon 19-Jan-15 08:21:54

OH FGS. As you can tell, I am not quite awake <drinks coffee>

I am obviously talking about subtraction. I might ask MN to change the title, so I don't have a billion people missing this correction and telling me I am more stupid than I actually am

diamondage Mon 19-Jan-15 08:28:24

Reading your post has left me a little confused too. Finding the difference refers to subtraction, not division, and your sum looks like column subtraction too? Is it ok to clarify if the sum is division or subtraction, or am I missing something obvious (quite possible) in which case apologies!

My DD has learnt column subtraction and would do that sum by breaking into the tens column (which has 5) and taking 10 from it, leaving 4 tens and putting the borrowed 10 into the units column etc. But I'm not sure if that's the formula you're trying to describe.

If it's division I'm as stumped as you!

diamondage Mon 19-Jan-15 08:29:29

Oops cross post!!!

Try looking up column subtraction on BBC bite size!!!

Mon 19-Jan-15 08:44:51

thanks diamond I suspect I'll leave a few people confused with my thread. I normally need at least 2 cups of coffee before I can hold any sensible conversation and today I am on leave recovering from an op so my day started later than usual And thanks for the unMNy polite way of pointing out my error, I was (am still) expecting, you twit, it's subtraction, not division.

I also tried looking it up this morning, after writing in DD's contact book, so i didn't forget, and I now know why the heck I was getting more confused. I am possibly less bad at maths than I thought...

I'll go take a look at the BBC website with my second cup of coffee, thank you

Mon 19-Jan-15 08:47:17

and the way you are talking about it diamond makes sense, DD was explaining it in a different way, or rather, not really able to explain it. She could do it for most of the sums then (probably too tired) got muddled and couldn't explain so I could understand what she was trying to do, so I was like [huh?] and then she got upset so we took a break. Admittedly, leaving it until Sunday is not ideal, if it was done earlier I could have learnt it and reviewed it, but life gets in the way of doing things properly.

diamondage Mon 19-Jan-15 09:50:05

No worries! This explains various methods for column subtraction www.11plusforparents.co.uk/Maths/writtensub.html
But we just use the final method (too many methods just confuse DD).

It's also really good to practice a sum like 300 - 169, where you have to break into the 100 column, put a 9 in the 10s etc otherwise it can be a stumbling block.
Hope that helps

Mon 19-Jan-15 15:45:47

diamond thank you. The ones that break into the 100 are the one she struggled to use the formula on, so she does need a consistent method, and those will be the ones we will practise this week and onwards. I want to use the same method she is using at school so that she doesn't get confused, it's not like I am an expert at maths and be sure whatever I know is the best way.

Mon 19-Jan-15 18:39:08

Different schools use different methods I think, in Numeracy, so I can't say what the exact formula might be. But, it is really more important that children UNDERSTAND the concepts behind maths, and not just rely on rote learning or a formula; these will come into it as well, but I think the understanding is the important part. So this might help:

﻿QUOTE:

Practical things are best for grasping number concepts - bricks, Lego, beads, counters, money, shapes, weights, measuring, cooking.

Do adding, taking away, multiplication (repeated addition), division (sharing), using REAL OBJECTS as just 'numbers' can be too abstract for some children.

Number Bonds of Ten forms the basis of much maths, so try to learn them. Using Lego or something similar, use a LOT of bricks (of just TWO colours, if you have enough) lay them out so the pattern can be seen of one colour INCREASING while the other colour DECREASES. Lay them down, or build up like steps.

So:

ten of one colour none of other
nine of one colour one of other
eight of one colour two of other
seven of one colour three of other

etc,

then of course, the sides are equal at 5 and 5; after which the colours 'swap over' as to increasing/decreasing.

To learn TABLES, do them in groups that have a relationship, thus:

x2, x4, x8

x3, x6, x12

5 and 10 are easy

7 and 9 are rather harder.

Starting with TWO times TABLE, I always say: "Imagine the class is lining up in pairs; each child will have a partner, if there is an EVEN number in the class. If one child is left without a partner, then the number is ODD, because an odd one is left out."

Use Lego bricks again, lay them out in a column of 2 wide to learn 2x table. Go half way down the column, and move half the bricks up, so that now the column is 4 bricks wide. That gives the start of 4x table.

Then do similar things with 3x and 6x.

With 5x, try and count in 'fives', and notice the relationship with 'ten' - they will alternate, ending in 5 then 10.

It is important to try and UNDERSTAND the relationships between numbers, and not just learn them 'by rote'.

An inexpensive solar powered calculator (no battery to run out!) can help learn tables by 'repeated addition'. So: enter 2+2 and press = to give 4. KEEP PRESSING = and it should add on 2 each time, giving 2 times table.

There are good web sites, which can be fun to use :

www.ictgames.com/

www.resources.woodlands-junior.kent.sch.uk/maths/index.html

UNQUOTE

Tue 20-Jan-15 12:35:52

really useful information thank you ferguson, I agree it's not just about formulas, but understanding what numbers are about etc. I think that's why I was never good at it, as I struggled to understand the relationship between the formulas and 'real life', it was just too abstract for me, as it had no relationship for me to link it to.

Her school are doing times tables already, expectation that she will know them by end of Yr4. She has done them/doing them in the following order, and being awarded 'prizes for each group of three'

2, 5, 10 (she knows these, although we do reminders so they stay in her head)

3, 6, 11 ( she is working on 3 and 6)

4, 7, 9 (i think)

8, 12 (i think)

I like the visual aspect of what you posted, as her teacher has said any concept we want to use that helps the times tables sink in is good, and useful to use a few different ones. And she has tons of lego!

Tue 20-Jan-15 19:38:37

Glad to help a bit! Yes - I failed 'O' level maths in 1950, for just that reason - 'understanding' did not seem to be encouraged in those days.

However, a few years ago, during two years working in a secondary school, TAs were given the opportunity to do GCSE maths lessons after school, and sit the exam - which I passed: only sixty years late!

Yes: use different coloured bricks and lay them out to illustrate things:

Use squared paper to draw 'squares', and use different coloured pencils to colour in each 'layer'.

So: 4, 9, 16, 25, 36 etc. Then try to find out if there is a 'formula' that represents the increase in numbers in each layer.

A fun use of numbers, that she will probably have done, is 'data collection' and producing graphs or charts from the results.

So: record the kinds of shop in the High Street; count different kinds of vehicles passing by; animals, birds, trees, plants, in the local park. Or if she is 'outgoing', interview friends about their favourite: foods, bands, TV, eye or hair colour.

Tally the numbers, and produce charts or graphs. (You may even have a computer program that will process the results.)

If she plays an instrument and can read music, see how far she can get using the time value of notes (crotchets, minims, semi-breve etc) to create Numbers, including 'dotted notes' if she knows about them. So: crotchet=1, minim=2, semi-breve=4. (If she doesn't do any music, ignore this paragraph, as it will be meaningless!

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