Is it multiple of 3?
Can you divide it by 3?
The divisibility for rule for three is really useful to know.
A number is divisible by 3 if the sum of each digit is either 3, 6 or 9.
For example;
51 Add the two digits 5 + 1 = 6
The
answer is 6 so therefore 51 is a multiple of 3
109 Add the three digits 1 + 0 + 9 = 10 now add 1 + 0 = 1
The answer is not
a 3, 6 or 9 so 109 is not divisible by 3
4125 Add the digits 4 + 1 + 2 + 5 = 12
Add the
digits 1 + 2 = 3
4125 is a
multiple of 3
2715219 Add the digits 2 + 7 + 1 + 5 + 2 + 1 = 18 Add 1 + 8 = 9
2715219
is divisible by 3
Knowing
this rule is also useful for identifying numbers that are multiples of 6.The divisibility rule for 6 is that the number has to be even and the sum of the digits are divisible by 3.
For example:
72 Add the digits together 7 + 2 = 9
72
is a multiple of 6.
It is an even number and the sum of the digits is 9 and
therefore a multiple of 3.
93 Add the digits together 9 + 3 = 12 1 + 2 = 3
Although 93 is divisible by 3 it
is not divisible by 6 because it is an odd number.
My students really enjoy experimenting with numbers to see if they are multiples of 3 or divisible by 6. They especially enjoy creating small presentations to show others their maths skills.
