my child who is in year four ( age 8 ) as been given some subtraction homework ????

Question

Does anyone know the correct way to show him how to do it . I dont want to show him a way which will confuse him. One of the sums is :-

21 - 1 4 =
I know how i was taught is totally different to how they are taught today. Thankyou

Answer 1

i think this question shows what a good parent you are the way children are taught changes from 1 year to the next. Some who have answered this question are clearly ignorant and need some education themselves. Some children are at different levels in there class and no child is stupid .

Answer 2

Here, this would be an easy way to show your child. . .
Put the number that is being subtracted on top, then the one doing to the subtracting on the bottom. . .for example,
21
-14
_____

Show him that 4 is larger than 1, so you must get from the next number in the sequence, which is 2. . . So have him cross out the 1 and 2, and in place of the 2 put a one. . .so like this

1 then the 1 in 21 becomes 11
21
-14
____
7

so, 11-4=7, and 1-1=0, so the answer is 7. . .
I hope this helped, but I think I confused myself a little! LOL

Answer 3

The 2 in 21 is in the 10's place, and since you can't subtract 4 from 1, you have to borrow 10 from the 10's column. You write this by crossing out the 2 in 21, writing a 1 above it, then writing a 1 (to represent 10) above the 1. Then you're subtracting 4 from 11, which makes 7.

21
-14
=7

Answer 4

I teach Year 5 but I'm the maths co-ordinator so I am also familiar with what goes on in Year 4:
He will have been taught several methods, and unless the homework sheet specifies which method he is to use, he can use any method that suits him. Some options are:
A compact method (the traditional one where you write the 21 above the 14, then subtract),
Counting on using a number line:
Draw a line, put 14 on the left of it and 21 on the right, then use 'hops' to count on, e.g. 14 jump on 6 to 20, jump on 1 to 21, add up the numbers above the 'hops',
Subtraction by partitioning:
e.g.
20 + 1
- 10 + 4
--------------
= 10 + 11
- 10 + 4
---------------
= 0 + 7 = 7

Hope this helps.

Answer 5

21
- 14
____

____

You cant take 4 away from 1 so you score the 2 out and put in 1 to make 11 ----- 11 minus 4 = 7 and 1 -1 = 0. So the answer is 7.
My 9 year old son helped with this although it was the same way as i did at school.

Answer 6

When I was that age my teacher always got furious with me for doing maths in my head and not on the page. I found writing it down in the needlessly convoluted manner they taught to be a big farce which caused more mistakes than it solved. Later on I realised it was not about how well I did in the project - it was how easy the work was to mark.
I think these days children are taught by a variety of methods that differ from teacher to teacher. Show your son the basic method of subtraction and if he understands the basic concept then I doubt slight differences in methodology will confuse him.

Answer 7

7

Answer 8

use a number line. start at 14 then add how many jumps it takes to get to 21. if there are questions where the answer is more than 10 then use one jump as 10 this saves space on the number line check out the standards site for some examples or the ngfl website hope this helps.

Answer 9

i will try ..this way worked for my kids who are 7.

21
-14
----------

The key factor is to memorize this rule:
If the bottom right number (4) is larger that the top right number (1)...then you will always have to borrow from the top left number (2).

which makes the 2 turn into 1 and the top right number becomes 11. now 11 minus 4 is =7. and 1 minus 1 is 0.

Answer 10

I had that problem with my son. You have to show the correct working out procedure. I couldnt understand it myself it was so complicated. I was so tempted to just work the simple sums in my head and give him the answers but the teachers need to know exactly how they work it out for themselves. Why they have changed things around I have no idea. Sorry I cant help