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A number is divisible by 12 if it is divisible by 3 AND it is divisible by 4.

Rule 1a (Divisibility by 3): Add up all the digits of the number. Is this number divisible by 3?

Rule 1b (Divisibility by 4): Is the number formed by the last two digits of the original number (the number left after deleting the hundreds, thousands, millions etc) divisible by 4?

If the answer to 1a is NO, then the number is not divisible by 3 and so not divisible by 12. In this case, obviously, rule 1b is irrelevant.

If the answer to 1b is NO, then the number is not divisible by 4 and so not divisible by 12.

If the answer to both 1a and 1b is YES, then the number is divisible by 12.

Q: Write a rule to determine when a number is divisible by 12?

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That the number is divisible by 4* and the sum of its digits is a multiple of 3. *If the number has three of more digits then it is only necessary to look at the tens and units to determine if it is divisible by 4, as 4 is a factor of 100 and therefore of any multiple of 100. Examples : 75 : is not divisible by 4 although its digits total 12 which is a multiple of 3. 132 : is divisible by 4 as 32 is divisible by 4, and its digits total 6 which is divisible by 3, then 132 is divisible by 12.

Rule: If it is divisible by 2 and by 3Numbers are divisible by 6 if they are divisible by 3 and 2. Therefore, for example, since 18 is divisible by 3 and 2, it is also divisible by 6.The divisibility rule for 6 is, it can go into the number if 2 and 3 can also.

Use the divisibility rule for 10. If the number is divisible by 10, then it is obviously also divisible by 5.

To find out if a number is divisible by 8 the number must be divisible by 2 and 4!

The rule to decide if a number is divisible by 9 is to look at the sum of the digits. If the sum of the digits is divisible by 9, then so is the number.

Related questions

The rule is: if a number is divisible by 5 and 17 at the same time, that number is divisible by 85

The divisible rule for 2 is if the last digit of the number is 0,2,4,6, or 8. The divisible rule for 3 is if the last 2 digits of the number is divisible by 3,03,06,09,12,15,18,21,24,27,30,33,36,39,42,45,48,51,54,57,60,63,66,69,72,75,78,81,84,87,90,93,96, or 99.

That the number is divisible by 4* and the sum of its digits is a multiple of 3. *If the number has three of more digits then it is only necessary to look at the tens and units to determine if it is divisible by 4, as 4 is a factor of 100 and therefore of any multiple of 100. Examples : 75 : is not divisible by 4 although its digits total 12 which is a multiple of 3. 132 : is divisible by 4 as 32 is divisible by 4, and its digits total 6 which is divisible by 3, then 132 is divisible by 12.

Rule: If it is divisible by 2 and by 3Numbers are divisible by 6 if they are divisible by 3 and 2. Therefore, for example, since 18 is divisible by 3 and 2, it is also divisible by 6.The divisibility rule for 6 is, it can go into the number if 2 and 3 can also.

if the number is divisible by 2 and 3 then it is divisible by 6 =D

If a number is divisible by 2 (an even number) and 3 (the sum of the digits is divisible by 3) then the number is divisible by 6.

Use the divisibility rule for 10. If the number is divisible by 10, then it is obviously also divisible by 5.

To find out if a number is divisible by 8 the number must be divisible by 2 and 4!

The rule to decide if a number is divisible by 9 is to look at the sum of the digits. If the sum of the digits is divisible by 9, then so is the number.

a number is divisible by 12 if the number is also divisible by both 3 and 7. You mean a number is divisible by 21 if it is divisible by 3 and 7.

the divisibility rule for 2 is: The number is even;the last digit ends with a 2,4,6,8,10, etc.The divisibility rule fir 3 is: The sum of the number is divisible by 3The divisibility rule for 4 is: The last two digits are divisible by 4The divisibility rule for 5 is: The number ends with a 5 or 0The divisibility rule for 6 is: The sum CAN be divisible by 2 and or 3The divisibility rule for 9 is: The sum of the number is divisible by 9The divisibility rule for 10 is : The number ends with a 0

If the sum of the digits in a number is divisible by 3, then the original number is divisible by 3.