subtraction
Moderators: Section Moderators, Forum Moderators
subtraction
My daughter's primary school has standardized on a different method of subtraction from the carries that we'd taught her. For example, given
they are told to obtain an extra ten for the 6 by crossing out the 3 and replacing it with a 2. I suppose it gives a better intuition about "borrowing the ten", but it will be problematic when they come to 10001 - 23. Is this method common?
Code: Select all
36
- 19
Yes it has been in use for a good while now. I used that method when teaching in the 80s. Something to do with the 'borrow and pay back' method not being possible if done practically. With a complicated subtraction it is initially difficult borrowing from several columns away, but once done the rest of the calculation is then easier to complete.
use a number line - vertical subtraction is not necessary and confuses most children. Sums are never set out vertically in KS2, KS3 or GCSE exams -
http://www.mad4maths.com/parents/
http://www.mad4maths.com/parents/
Hi yoyo123
The "decomposing" method results in the child being given 18 - 9 as the most difficult possible sum. I am sure that most teachers could teach children that 18 - 9 = 9
I was taught this method from 1963 all the way through schooling and never cam across any other method.
When teaching maths I have always felt that the easiest method is the best.
Regards
Mike
The "decomposing" method results in the child being given 18 - 9 as the most difficult possible sum. I am sure that most teachers could teach children that 18 - 9 = 9
I was taught this method from 1963 all the way through schooling and never cam across any other method.
When teaching maths I have always felt that the easiest method is the best.
Regards
Mike
Mike Edwards is a co-author of The Tutors product range.
I hated decomposition , I was taught an entirely different method (take bottom number away from ten add result to teh top number if it is more than ninne put the "tens" digit in next column).
I had to learn decomposition by rote to teach iot and still got stuck!
I'm OK now but always use my method in my head when going round class marking as it comes naturally to me.
I had to learn decomposition by rote to teach iot and still got stuck!
I'm OK now but always use my method in my head when going round class marking as it comes naturally to me.