## Arithmetical Methods

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##### Arithmetical Methods

##### Arithmetical Methods

04-02-2015 4:44 PM

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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

__ Customer__ and Forum Moderator. Windows 10 Firefox 63.0 (64-bit)

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##### Re: Arithmetical Methods

##### Re: Arithmetical Methods

04-02-2015 4:55 PM

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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

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##### Re: Arithmetical Methods

##### Re: Arithmetical Methods

04-02-2015 4:58 PM

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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.

__ Customer__ and Forum Moderator. Windows 10 Firefox 63.0 (64-bit)

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##### Re: Arithmetical Methods

##### Re: Arithmetical Methods

04-02-2015 5:08 PM

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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

##### Re: Arithmetical Methods

04-02-2015 5:12 PM

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##### Re: Arithmetical Methods

##### Re: Arithmetical Methods

04-02-2015 5:36 PM

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##### Re: Arithmetical Methods

##### Re: Arithmetical Methods

04-02-2015 6:03 PM

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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

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##### Re: Arithmetical Methods

##### Re: Arithmetical Methods

04-02-2015 6:31 PM

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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

##### Re: Arithmetical Methods

05-02-2015 1:51 AM

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Quote from: artmo Would the teacher not run through this again if asked

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

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

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##### Re: Arithmetical Methods

##### Re: Arithmetical Methods

05-02-2015 8:35 AM

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

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.

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##### Re: Arithmetical Methods

##### Re: Arithmetical Methods

05-02-2015 9:13 AM

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##### Re: Arithmetical Methods

##### Re: Arithmetical Methods

05-02-2015 9:19 AM

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I also firmly believe that children should not be allowed the use of calculators until they know how to do the sums long-hand.

**Forum Moderator** and ** Customer***Courage is resistance to fear, mastery of fear, not absence of fear - Mark Twain*

He who feared he would not succeed sat still

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##### Re: Arithmetical Methods

##### Re: Arithmetical Methods

05-02-2015 10:33 AM

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Younger readers won't understand that comment.

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##### Re: Arithmetical Methods

##### Re: Arithmetical Methods

05-02-2015 10:44 AM

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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

##### Re: Arithmetical Methods

05-02-2015 11:01 AM

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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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