Divisibility By 4

Is it divisible by four?
This little math trick will show you whether
a number is divisible by four or not.

So, this is how it works.

Let's look at 1234

Does 4 divide evenly into 1234?

For 4 to divide into any number we have
to make sure that the last number is even

If it is an odd number, there is no way it will go in evenly.
So, for example, 4 will not go evenly into 1233 or 1235

Now we know that for 4 to divide evenly into any
number the number has to end with an even number.

Back to the question...

4 into 1234, the solution:

Take the last number and add it to 2 times the second last number

If 4 goes evenly into this number then you know
that 4 will go evenly into the whole number.

So
4 + (2 X 3) = 10
4 goes into 10 two times with a remainder of 2 so it does not go in evenly.

Therefore 4 into 1234 does not go in completely.

Let’s try 4 into 3436546

So, from our example, take the last number, 6 and add it to
two times the penultimate number, 4

6 + (2 X 4) = 14
4 goes into 14 three times with two remainder.
So it doesn't go in evenly.

Let's try one more.

4 into 212334436

6 + (2 X 3) = 12
4 goes into 12 three times with 0 remainder.

Therefore 4 goes into 234436 evenly.

So what use is this trick to you?
Well if you have learnt the tutorial at Memorymentor.com
about telling the day in any year, then you can use it in
working out whether the year you are calculating is a leap year or not.