GMAT Digits

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GMAT Digits

by abhi75 » Mon Jun 16, 2008 2:13 pm
If M is a positive integer, then M^3 has how many digits ?
1) M has 3 digits
2) M^2 has 5 digits.

Is there any better way to pick up easy numbers on this type of problem.

The OA is E.

Thanks.
-A
Source: — Data Sufficiency |

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Re: GMAT Digits

by durgesh79 » Tue Jun 17, 2008 12:34 am
abhi75 wrote:If M is a positive integer, then M^3 has how many digits ?
1) M has 3 digits
2) M^2 has 5 digits.

Is there any better way to pick up easy numbers on this type of problem.

The OA is E.

Thanks.
-A
this is how i did it

statement 1 : 99 < M < 1000, clearly not suff
statement 2 : 10000 <= M^2 < 100000
100 <= M <= 316

Now 1^3 = 1, 2^3 = 8, 3^3 = 27. so we know 300^3 will have more digits than 200^3.

E