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Thought-Process to Discover Knowledge

Welcome to nubtrek.

Books and other education websites provide "matter-of-fact" knowledge. Instead, nubtrek provides a thought-process to discover knowledge.

In each of the topic, the outline of the thought-process, for that topic, is provided for learners and educators.

Read in the blogs more about the unique learning experience at nubtrek.continue

In this page, a simple overview of the divisibility test for `4` is provided.



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Consider `100` and `24`. Which of these is divisible by `4`?

Check this by long division method.

  • `100`
  • `24`
  • both the above
  • both the above

The answer is "both `100` and `24`"

The multiples of `4` have the property that last two digits are divisible by `4`.

Explanation for the curious mind

A large number like `2344` can be given as `23xx100+44`.

It was learned that if one addend is divisible, then the divisibility is decided by the other addend.

`23xx100` is always divisible by `4` as `100=25xx4`.

So, the divisibility test is done in `44`, that is the tens and units digits.

Test for Divisibility by 4 : If the last `2` digits (tens and units place value positions) of the number is divisible by `4` then the number is divisible by `4`.

Is `2018` divisible by `4`?

  • Yes
  • No
  • No

The answer is "No". Checking the tens and units digits `18`, it is concluded that the number is not divisible by `4`.

Is `920` divisible by `4`?

  • Yes
  • Yes
  • No

The answer is "Yes". Checking the tens and units digits `20`, it is concluded that the number is divisible by `4`.

                            
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