### Find the composite number from 1 to 100 just in 5 second (Math Composite Number Shortcut tricks)...

An interesting math shortcut composite number trick for find the composite number from 1 to 100 (Just in 5 second)

Before starting this math shortcuts composite number trick let us revise the composite number defination.

Composite Number

"A number that can be divided exactly by numbers other than 1 or itself is called a composite number" i.e 4, 6, 8, 9, 10... notice that 1 is not included in composite number and 2, 3 are in prime number list therefore composite number are starting from 4.

This math shortcuts composite number trick is used to find all composite numbers between 1 and 100.

First arrange numbers in a table like following chart. Enter 6 numbers in each row then start the next row.

1- Cross out 1 because according to defination it is not composite

2- Cross out 2 with a Red color then draw red line (for cross out) on all multiple of 2.

3- Cross out 3 with a blue color then draw blue line (for composite) on all multiple of 3.

4- Cross out 5 with a Green color then draw Green line (for composite) on all multiple of 5.

5- Cross out 7 with a Yellow color then draw Yellow line (for composite) on all multiple of 7.

6- Cross out 11 and search for multiple of 11 in remaining number. We notice that there is no multiple of 11 in remaining numbers. Cross out the remaining number where no line was drawn.

7- No need further process because there is no multiple exist in remaining numbers. Non crossed number where coloured line was drown are composite number.

Thefore the composite number between 1 and 100 are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97.

They are total 25.

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##### NUMBERING SYSTEM QUESTION

Is zero even number or odd number (Even, Odd, Both, Neither even nor odd)...?
What is the lowest odd prime number (2, 3, -2, -3)...?
What are the consective prime number (2 and 3, 5 and 7, 11 and 13, all above)...?
Which number is prime number (1, 39, 49, None)...?
1 is prime or composite number (Prime, Composite, both, Neither Prime nor composite)..?
Give me numbers which are neither prime nor composite (0, 1, 0 and 1, None)?
All non prime number are also the composite number. (True or False)?
Which number neither prime nor composite (1, 29, 39, None)...?
What is the largest composite number less than 20 (17,18,19,20). ?
What is largest composite number less then 30 (23, 25, 28, 29)?
The number 4, 6, 8, 9, ... are (odd, even, prime, composite number) ...?
All even number greater then 2 are composite number (True, False)... ?
How many prime number are between 10 and 30 (5, 6, 7, 8)?
How many prime number are between 1 and 100 (25, 27, 29, 31)?
Which of the following is prime number (703,731,797,729)...?
##### MATH SHORTCUTS

Addition Shortcuts
Division Shortcuts