Best Answer

Add together all the digits until you get a single figure answer. If that's divisible by three, so's the original number. E.g. 4,239 broken down to 4 + 2 + 3 + 9 = 18; 1 + 8 = 9, which is a multiple of 3. The original number is therefore divisible by 3

Q: How do you know if a number divisible by 3?

Write your answer...

Submit

Still have questions?

Continue Learning about Algebra

A number is divisible by 2 if that number is an even number, which means it ends in 0, 2, 4, 6, or 8. A number is divisible by 3 if the sum of its digits is evenly divisible by 3.

27 for one then there's 36, 45, 54, 18 in short, any number divisible by 9 is also divisible by 3

'121'. 121/3 = 40.3333..... Not divisible. 121/5 any number that does not end in '5' or '0' is not divisible by '5' 121/7 = 17 3/7 Not divisible. 121/9 any number whose digits do not sum to nine is not divisible by '9' ; 1+2+1 = 4

132

-4

Related questions

the number will also be divisible by 3 and 2

A number that is divisible by 15 is divisible both by 5 and 3 A number is divisible by 5 if it ends with 0 or 5 A number is divisible by 3 if the sum of its digits is divisible by 3 e.g. 4035 is divisible by 15 as it ends with a 5 and 4+0+3+5=12 which is divisible by 3

No, 3 is not a factor of 47. A quick way to know that is to add the digits in the number. If they add up to a number that is divisible by 3, the number itself is divisible by 3. If they don't, the number is not divisible by 3.

If the sum of the digits can be divided by 3. 93 is divisible by 3 because 9+3=12 we know 12 is divisible by 3 because 1+2=3 so the number is divisible by 3.

Add up the digits of the number. If the sum is divisible by 3, then the number itself is divisible by 3. Ex: Is 781 divisible by 3? 7+8+1=16 16 is not divisible by 3 so neither is 781 Is 903 divisible by 3? 9+0+3= 12 12 is divisible by 3 so 903 is divisible by 3

If a number is even, it's divisible by two. If the digits of a number add up to a multiple of 3, it's a multiple of 3. For example, 342 is divisible by 3 because 3 + 4 + 2 = 9 and 9 is divisible by 3.

add all the digits of the number and check if it is divisible by 3. eg-3321=3+3+2+1=9=divisible by three.the same works for 9.

The way to know if a number is divisible by 3 is if its digit sum adds up to a number that is divisible by 3 (3, 6 or 9). The way to know if a number is divisible by 2 is if that number is even. That is, a number is divisible by two if the units are 0, 2, 4, 6 or 8. A number is divisible by 6 if it meets both these rules. In this case, 402 has the digit sum 6, and the units value is 2. Therefore, we can say that 402 is divisible by 6.

Converse:If a number is divisible by 3, then every number of a digit is divisible by three. Inverse: If every digit of a number is not divisible by 3 then the number is not divisible by 3? Contrapositive:If a number is not divisible by 3, then every number of a digit is not divisible by three.

Quickly check to see whether it's divisible by both 2 and 3. Here's how to do that easily: -- The number is divisible by 2 if it's an even number . . . the last digit is 2, 4, 6, 8, or 0. -- The number is divisible by 3 if the sum of its digits is divisible by 3.

35 is not divisible by 3.

To determine if a number is divisible by 6, it must be divisible by both 2 and 3. To determine if a number is divisible by 2, it should be even - in other words, it should end with 0, 2, 4, 6, or 8. To determine if a number is divisible by 3, the sum of its digits should be divisible by 3. 54,132 is an even number, so it is divisible by 2. 5 + 4 + 1 + 3 + 2 = 15, which is divisible by 3, so 54,132 is divisible by 3. Since 54,132 is divisible by both 2 and 3, it is divisible by 6.