We are able to enhance student learning in mathematics with tricks. There are many tricks to teach pupil divisibility in mathematics. Some tricks are listed here. If you know others, please let me know.
A Number is Divisible By 2 if :Its One's Digit is divisible by 2.
E.g. 368: 8 is divisible by 2, therefore 368 is divisible by 2.
A Number is Divisible By 3 if :The Sum of its digits is divisible by 3.
E.g. 732: 7 + 3 + 2 = 12, 12 is divisible by 3.
Therefore 732 is divisible by 3.
For example: 12123 (1+2+1+2+3=9) 9 is divisible by 3, therefore 12123 is too!
A Number is Divisible By 4 if :If the last two digits represent a number divisible by 4
E.g. 524: 24 is divisible by 4, therefore 524 is
divisible by 4.
A Number is Divisible By 5 if :It ends in Zero or Five.
E.g. 105: 105 ends in a Five, therefore 105 is
divisible by 5.
A Number is Divisible By 6 if :It is divisible by BOTH 2 and 3.
E.g. 786: 6 is divisible by 2, therefore 786 is
divisible by 2.
7 + 8 + 6 =21 and 21 is divisible by 3,
therefore 786 is divisible by 3.
Hence 786 is divisible by 6.
A Number is Divisible By 7 if :Take the last digit, double it and subtract it from the rest of its numbers. Check if the
result is divisible by 7.
E.g. 28: 8 x 2 = 16, 16 – 2 = 14 and 14 is
divisible by 7. Therefore 28 is divisible by 7.
Example: Is 2016 divisible by 7?
6(1) + 1(3) + 0(2) + 2(6) = 21
21 is divisible by 7 and we can now say that 2016 is also divisible by 7.
A Number is Divisible By 8 if :The last three digits represent a number divisible by 8.
E.g. 3 792: 792 is divisible by 8, therefore
3 792 is divisible by 8.
Example: 6008 - The last 3 digits are divisible by one, therefore, so is 6008.
A Number is Divisible By 9 if :The Sum of its digits is divisible by 9.
E.g. 36 792: 3+ 6 + 7 + 9 + 2 = 27 and
27 is divisible by 9. Therefore 36 792 is
divisible by 9.
For example: 43785 (4+3+7+8+5=27) 27 is divisible by 9, therefore 43785 is too!
A Number is Divisible By 10 if :It ends in a zero.
E.g. 320: 320 ends in a zero, therefore 320 is
divisible by 10.
A Number is Divisible By 11 if :The difference between the sum of its
odd-position digits and the sum of its even-position digits is divisible by 11.
E.g. 957: (9+ 7) – 5 = 11 and 11 is divisible by 11.
Therefore 957 is divisible by 11.
A Number is Divisible By 12 if :It is divisible by BOTH 3 and 4.
E.g. 684: 6 + 8 + 4 =18 and 18 is divisible by 3,
therefore 684 is divisible by 3.
84 is divisible by 4, therefore 684 is divisible by 4.
Hence 684 is divisible by 12.
10 comments:
Dear Mr Lee,
I have read your article and thought that it was very interesting.
I know 5 out of the 11 you have posted.
For the other 6,I copied them down for my future use.
Dear Mr Lee,
I have read your article. It was awesome! You are so smart! Before I read it, I thought there would never be a pattern for the number 6 and onwards. Did you learn it or thought it out by yourself?
368 is divisible by 2 therefore 368 is divisible by 2??!!
Daniel Cheng 4F
Comment on wrong account.
Daniel Cheng 4F
hello Mr Lee I didn't know there was such a trick for division on 11 and 12.who thought you that? or did you learn it yourself?
I think I just learnt that! Or did I learn it in Primary already?
There are also interesting "tricks" for multiplication by 11.
dear Mr Lee,
I am impressed!I only knew 3/11 of that!I read Darren Ang's comment and decided to imitate him and copy the 8/11 that I did not know for my future use.
Nicholas Foong(27)4F
Hi mr lee,
i have read ur article,it was nice.
i only know from the 1-5 but from 6 onwards i dont know.thx 4 this information Mr Lee
Yup. I just learnt that in secondary!
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