The number 1 0 0 3 0 0 3 0 0 1 is the product of N (not necessarily distinct) primes. What is the value of N ?
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Great explanation of how to easily find the prime factors in this case.
Beautiful solution!
Awesome
awesome
nice
what a thinking!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Awesome
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great answer
What a nice approach!
Superb concentration on numbers......
Hats Off..:)
Great !!!!!!!
It is awesome & easy to understand & can also be used for such other problems.
We notice the symmetry in the number. 1,3,3,1. This should remind us of Pascal's triangle. In particular, the expansion ( x + 1 ) 3 = x 3 + 3 x 2 + 3 x + 1 . Letting x = 1 0 3 we get ( 1 0 3 + 1 ) 3 = 1 0 9 + 3 ⋅ 1 0 6 + 3 ⋅ 1 0 3 + 1 = 1 0 0 3 0 0 3 0 0 1 , which is our number. So we want the number of prime divisors of ( 1 0 3 + 1 ) 3 = ( 1 0 0 1 ) 3 = ( 7 ⋅ 1 1 ⋅ 1 3 ) 3 = 7 3 ⋅ 1 1 3 ⋅ 1 3 3 , so the answer is 3 + 3 + 3 = 9 .
Remark: 1001=7 11 13 is a very common factorization in the math competition world - strap it to your tool belt!
Wonderful
Remark should say "1001 = 7 * 11 * 13".
Outstanding
superb ....
awesome.
1003003001 = 7^3 * 11^3 * 13^3 ,so 1003003001 has a 3 + 3 + 3 = 9 product
JOKES
1 0 0 3 0 0 3 0 0 1 is 1 0 0 1 3 because ( 1 0 0 0 + 1 ) 3 = 1 0 0 0 3 + 3 ⋅ 1 0 0 0 2 + 3 ⋅ 1 0 0 0 + 1 1 0 0 1 = 7 ⋅ 1 1 ⋅ 1 3 , 3 primes. When you cube it, you multiply these three times, to get 9 primes.
CALCULATOR JINDA BAD
1003003001 = 7x7x7x13x13x13x11x11X11 , 9 primes
1003003001= (1001)^3 = (7 × 11 × 13)^3 = 7^3 × 11^3 × 13^3
Prime factorisation of 1003003001 is
7 X 7 X 7 X 11 X 11 X 11 X 13 X 13 X 13
They are 9.
The number 1003003001=7x7x7x11x11x11x13x13x13 is the product of 9 primes.
1 003 003 001 = 1001 x 1001 x 1001 = (7 x 11 x 13)^3 3 x 3 = 9
From the binomial theorem (or Pascal's triangle) we see that 1003003001 is a perfect cube
∛(1003003001) = 1001 = 7•11•13, which has 3 prime factors, so N = 3•3 = 9
when we do prime factorization of 1003003001 we get, 11^3 * 13^3 * 7^3 so there are total 9 prime factors....:)
A simple method for ESTIMATING the number, n, of prime factors for a large number N can be used:
n ~ ln ( ln ( N ) ) ^ 2
For 1003003001, ln ( ln ( 1003003001 ) ) ^ 2 = 9.1894... ~ 9
This estimation becomes more and more accurate with greater numbers
Very Simple it's 7 x 7 x 7 x 11 x 11 x 11 x 13 x 13 x 13 =1003003001 All are prime and total are 9!!
Start by dividing with prime no. As u will go u will see it will result in.. 7x7x7x11x11x11x13x13x13
1003003001 = 1001^3 1001= 1 7 11*13 total 3 prime numbers, 3 times. That makes it 9
Complete proof :
Note that 1 0 0 3 0 0 3 0 0 1 = 7 3 ⋅ 1 1 3 ⋅ 1 3 3 and 7 , 1 1 , 1 3 are primes, so it is the product of N = 3 + 3 + 3 = 9 primes.
Motivation :
1 0 0 3 0 0 3 0 0 1 looks similar to 1 3 3 1 = 1 1 3 . Indeed, if we remember the binomial expansion of ( x + 1 ) 3 = x 3 + 3 x 2 + 3 x + 1 , we can see that 1 1 3 = 1 3 3 1 can be obtained from the binomial expansion by x = 1 1 . In this case, 1 0 0 3 0 0 3 0 0 1 can be obtained from the binomial expansion by x = 1 0 0 0 , so 1 0 0 3 0 0 3 0 0 1 = 1 0 0 1 3 . Finally, 1 0 0 1 = 7 ⋅ 1 1 ⋅ 1 3 is a well known factorization.
"we can see that 1 1 3 = 1 3 3 1 can be obtained from the binomial expansion by x = 1 1 "
I realize that typo >_< Should be x = 1 0 .
WE NEED TO PRIME FACTORIZE THE GIVEN NUMBER. 1003003001= 7 x 7 x 7 x 13 x 13 x 13 x 11x 11 x 11
Test first for the factors by dividing 1003003001 to all possible prime numbers, starting from 1, 2, 3, 5, 7, 11, 13, so on.. and check which will result a whole number.
Then you'll notice that it divides by 7, 11, and 13, resulting into whole number.
Prime factorization = 7 ∗ 1 1 ∗ 1 3 = 1 0 0 1
Next, divide the given number to its prime factorization:
1 0 0 3 0 0 3 0 0 1 / 1 0 0 1 = 1 0 0 2 0 0 1
Repeating the process by dividing it to its proper prime factorization... 1 0 0 2 0 0 1 / 1 0 0 1 = 1 0 0 1
then 1 0 0 1 / 1 0 0 1 = 1
Therefore: 1 0 0 3 0 0 3 0 0 1 = 7 3 × 1 1 3 × 1 3 3 and N = 3 + 3 + 3 = 9
you have to prime factorise it. it is hard i know but. you can use a calculator if you want. But what is the divisor ? First it's 7 Like this carry on till you have got a less number. Then since you have three tries you can guess if you like it. But it's luck The correct answer is 9.
1 0 0 3 0 0 3 0 0 1 is clearly not even, nor is it divisible by 3 because its digit sum is not and it isn't divisible by 5 . Now 7 3 × 2 9 2 4 2 0 7 = 1 0 0 3 0 0 3 0 0 1 and 7 doesn't divide 2 9 2 4 2 0 7 , but continuing dividing by the next prime as many times as possible we find 1 0 0 3 0 0 3 0 0 1 = 7 3 × 1 1 3 × 1 3 3 which is nine primes.
1003003001=1000^3+3 1000^2 1^2+3 1000^1 1^2+1^3=(1000+1)^3 1001=13 11 7 ==> 1003003001=13^3 11^3 7^3
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Note that ( 1 0 x + 1 ) 3 = 1 0 3 x + 3 × 1 0 2 x + 3 × 1 0 x + 1
For x=1, 1 1 3 = 1 3 3 1
For x=2, 1 0 1 3 = 1 0 3 0 3 0 1
And for x=3, 1 0 0 1 3 = 1 0 0 3 0 0 3 0 0 1
By quick check of factoring rules, we see 1001 is divisible by 7, 11, and therefore 13, so 1 0 0 3 0 0 3 0 0 1 = 7 3 × 1 1 3 × 1 3 3 which gives us 9 prime factors.