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Arithmetical Methods

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Arithmetical Methods

My grandson was doing some arithmetic homework which included some sums consisting of a 4 digit whole number divided by 3 which resulted in a recurring decimal.
He was having difficulty because of a missed lesson due to a hospital appointment.
He asked his mum for help who in turn asked me to assess her calculation.
The point of this tale is that each of our methods of calculating the answer on paper were different because of the generation gap.
How are parents or grandparents supposed to help children with homework if the goalposts keep getting moved Undecided
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Re: Arithmetical Methods

Would the teacher not run through this again if asked Undecided
The example you give though really shows why pupils should not be allowed to go on holiday during term time. How will they ever catch up Undecided
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Re: Arithmetical Methods

His mother suggested he write down the sums in his book and put 'need help' at the side of each.
His teacher is a good one and I'm sure he will help.
A £60 fine versus a £600+ difference in holiday costs clouds peoples' vision.
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VileReynard
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Re: Arithmetical Methods

Add up the digits of the large number, repeating until you have a single digit.
If this is divisible by 3, the original number is divisible by 3.
Works for 9 too.
Example:- 7281 / 3
7 + 2 + 8 +1 = 18
1 + 8 = 9
So 7281 is exactly divisible by 3 (and 9).

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Re: Arithmetical Methods

Fell asleep in the hay counting lambs this afternoon! fortunately whole numbers only!
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Re: Arithmetical Methods

That's a sheepish excuse Smiley Smiley
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Re: Arithmetical Methods

I went back to College 6 months ago - I'm old enough to be the father of every student there.
A bit of a culture shock seeing students who can't really be bothered to learn. One of my tutors is also the father of a kid I was best mates with at school over 35 years ago  Grin
alanf
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Re: Arithmetical Methods

Quote from: vilefoxdemonofdoom
Add up the digits of the large number, repeating until you have a single digit.
If this is divisible by 3, the original number is divisible by 3.
Works for 9 too.

I learned this as a technique for checking sums. For example to check the total calculated by adding a column of numbers
a) Reduce the total to a single digit.
b) Reduce each number in the column to a single digit. (That digit is the remainder if that number is divided by 9 or 9 if the remainder is zero).
c) Add each of those single digits and reduce again to a single digit.
d) The single digit found in a) should be the same as in c)
This technique can prove if a total is incorrect but it cannot prove that it is correct only improve the odds that the it is correct by catching most errors.
There was another technique for checking using remainders of 11 but I cannot recall it. I'll post if I can find it.
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Re: Arithmetical Methods

Quote from: artmo
Would the teacher not run through this again if asked Undecided
The example you give though really shows why pupils should not be allowed to go on holiday during term time. How will they ever catch up Undecided

Well back in the day (sheesh now i feel old) these lessons would be repeated until it was drummed into us. Now.. well.. seems like everyone is too busy learning to use email, word, excel and ipads rather than anything thats really productive Roll eyes
I need a new signature... i'm bored of the old one!
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Re: Arithmetical Methods

Quote from: Strat
How are parents or grandparents supposed to help children with homework if the goalposts keep getting moved Undecided

Our local primary school recognizes that the mathematical strategies taught to the children are different from what the parents learnt, so every year the parents and carers are invited to attend an all afternoon session to be shown the different techniques being taught, and receive a handout crib-sheet for use when they need to help the children with their homework.
Smiley
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Re: Arithmetical Methods

The latest "target" of knowing your 12 times table by the time you leave primary school. So unambitious.  We had to go up to the 13 times table by age 8 in our North Buckinghamshire village Primary School.
Now Zen, but a +Net residue.
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Re: Arithmetical Methods

Knowing the twelve times table by heart has held me in good stead over the years. I think it was a great shame it was dropped. To be able to look at two numbers and instantly know the result puts some of today's youngsters in awe Roll eyes
I also firmly believe that children should not be allowed the use of calculators until they know how to do the sums long-hand.

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VileReynard
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Re: Arithmetical Methods

We had to learn how to add/subtract two sterling amounts - in £SD
Younger readers won't understand that comment.  Cheesy

RobPN
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Re: Arithmetical Methods

Quote from: AlaricAdair
The latest "target" of knowing your 12 times table by the time you leave primary school ...

I remember the tune but I've forgotten the words Miss ...
... I'll get my coat.
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Re: Arithmetical Methods

Quote from: purleigh
Our local primary school recognizes that the mathematical strategies taught to the children are different from what the parents learnt, so every year the parents and carers are invited to attend an all afternoon session to be shown the different techniques being taught, and receive a handout crib-sheet for use when they need to help the children with their homework.

Yes I've heard of this being done locally as well. It's something parents feel to be a good idea.
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