maths divisibility rules

[xavier]

could someone please tell my what the divisibility rules for the numbers 3, 4, 5, 6, 8, 9 areit would be greatly appreciated. thankyou

[jenstar]

If you add up the digits of a number and the total is divisible by 3, then so is the original number. Ditto if the total is divisible by 9, the original number is divisible by 9. (If the total you get from adding the digits is very large, you can add the digits of the total together to get a smaller number). If the number is divisible by 3 and is even, then it's divisible by six as well. A whole number is divisible by 5 if it ends in 5 or 0, simple as that. Any whole number is divisible by four if the number formed by the last two digits is divisible by four, e.g. 82354752 is divisible by 4 because 52 is divisible by 4.

[pinus]

This takes me back Divisible by 3 Add the digits, and if that total is a multiple of 3, the original number is divisible by 3 547 5+4+7 = 16 which is not a multiple of 3, therefore 547 not divisible by 3 Multiple of 4 Any exact number of hundreds is a multiple of 4, so we only need to look at the last two digits -- if they are a multiple of 4, so is the full number Multiple of 6 The EVEN multiples of 3 are multiples of 6 Multiple of 8 Any exact number of thousands is a multiple of 8, so we only need to look at the last three digits -- if they are a multiple of 8, so is the full number 35912 912 is an exact multiple of 8, so 35912 is a multiple of 8 (as are 36912, 6556565657744912, etc) Multiple of 9 Add the digits, and if that total is a multiple of 9, the original number is divisible by 9 35568 3+5+5+6+8 = 27 which is a multiple of 9, therefore 35568 is a multiple of 9 Multiple of 11 The difference between the sums of the odd digits and the even digits is 0 or a multiple of 11 35915 3+9+5 = 17 5+1 = 6 difference 11 therefore 35915 is a multiple of 11

[xavier]

thank you pinus