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Just to refresh basic divisibility rules... A number is

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Intern
Joined: 24 Sep 2008
Posts: 19
Followers: 0

Kudos [?]: 53 [13] , given: 0

Just to refresh basic divisibility rules... A number is [#permalink]  09 Oct 2008, 01:52
13
KUDOS
Just to refresh basic divisibility rules...

A number is divisible by 2: unit digit is even i.e 128, 146 44 etc. (tough one)

A number is divisible by 3: sum of digits is divisible by 3 i.e 102, 192, 99 etc

A number is divisible by 4 when the number formed by last two right hand digits is divisible by '4' i.e. 576, 144

A number is divisible by 5 when its uni digit is either five or zero: e.g. 11155, 3970, 145 etc.

A number is divisible by 6 when it is divisible by 2 & 3 both e.g 714, 509796, 1728 etc.

A number is divisible by 8 when the number formed by the last three right hand digits is divisible by 8 i.e. 512, 4096, 1304

A number is divisible by 9 when the sum of its digits is divisible by 9 e.g. 1287, 11583, 2304 etc.

A number is divisible by 11 when the difference between the sums of digits in the odd and even places is either zero or a multiople of 11 i.e 17259, 62468252, 12221 etc.
For the number 17259: sum of digits in even places = 7+5 = 12, Sum of digits in the odd Places = 1+2+9=12
hence 12-12 =0 So the number is divisible by 11.

Thanks.
VP
Joined: 30 Jun 2008
Posts: 1048
Followers: 11

Kudos [?]: 340 [0], given: 1

Re: Very Basic Divisiblity rules [#permalink]  09 Oct 2008, 02:08
kam wrote:
Just to refresh basic divisibility rules...

A number is divisible by 2: unit digit is even i.e 128, 146 44 etc. (tough one)

A number is divisible by 3: sum of digits is divisible by 3 i.e 102, 192, 99 etc

A number is divisible by 4 when the number formed by last two right hand digits is divisible by '4' i.e. 576, 144

A number is divisible by 5 when its uni digit is either five or zero: e.g. 11155, 3970, 145 etc.

A number is divisible by 6 when it is divisible by 2 & 3 both e.g 714, 509796, 1728 etc.

A number is divisible by 8 when the number formed by the last three right hand digits is divisible by 8 i.e. 512, 4096, 1304

A number is divisible by 9 when the sum of its digits is divisible by 9 e.g. 1287, 11583, 2304 etc.

A number is divisible by 11 when the difference between the sums of digits in the odd and even places is either zero or a multiople of 11 i.e 17259, 62468252, 12221 etc.
For the number 17259: sum of digits in even places = 7+5 = 12, Sum of digits in the odd Places = 1+2+9=12
hence 12-12 =0 So the number is divisible by 11.

Thanks.

Nice post ... But isn't it weird that there have been only 3 visits and no replies to this post but 12 KUDOS

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Intern
Joined: 24 Sep 2008
Posts: 19
Followers: 0

Kudos [?]: 53 [0], given: 0

Re: Very Basic Divisiblity rules [#permalink]  09 Oct 2008, 03:13
hmmm visits are more than kudos but it still seems weird.. can someone give multiple kudos during one visit ?
Re: Very Basic Divisiblity rules   [#permalink] 09 Oct 2008, 03:13
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