Question 19792
Prime numbers are numbers which cannot be divided by another other number completely.example:2,3,5,7,11,etc
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Factors are numbers which divide other numbers without leaving a remainder
eg: 3 is a factor of 9,but 2 is not a factor of 9 since it leaves a remainder of 1.
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Now prime factors means all the prime numbers that are factors of the given number
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we have been given 90
90 can be divided by short division as,
<font color=blue><pre>
2|90
3|45
3|15
5| 5
 | 1
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</pre></font>
So the prime factors of 90 are:
90=2*3*3*5
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this means suppose you have a number,say 28,28 can be divided by 14.but 14 is not a prime number,14=7*2.so we can write 28=2*7*2.those are its prime factors
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Hope this helps,
Prabhat