for any +ve integer n, the length of n is defined as the number of prime factors whose product is n. For example, the length of 75 is 3, since 75 = 3 X 5 X 5. how many two-digit integers have length 6?
1. none
2. 1
3. 2
4. 3
5. 4
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g.shankaran
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IMO 2. 1g.shankaran wrote:for any +ve integer n, the length of n is defined as the number of prime factors whose product is n. For example, the length of 75 is 3, since 75 = 3 X 5 X 5. how many two-digit integers have length 6?
1. none
2. 1
3. 2
4. 3
5. 4
because 2^6=64 if you try to replace any 2 from 3 it will be
2*2*2*2*2*3=106 which is 3 digit no.
so for 2 digit no it will be 64 only, which has 6 length.
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vinayreguri
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Ans 2. 2 numbers in total.
2*2*2*2*2*2=64
2*2*2*2*2*3=96
I see these questions in MGMAT forums also.
2*2*2*2*2*2=64
2*2*2*2*2*3=96
I see these questions in MGMAT forums also.
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Geva@EconomistGMAT
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Slow down, score more. It's always good to spend an extra 10 seconds taking another look at your logical path before committing to an answer - try to pick up on hidden assumptions that you're making (such as that fact that the prime factors don't need to all be the same, in the case above).Calvin123 wrote:vinayreguri wrote:Ans 2. 2 numbers in total.
2*2*2*2*2*2=64
2*2*2*2*2*3=96
I see these questions in MGMAT forums also.
My bad.. ans must be 2, i did silly calculation mistake
