For all positive integers \(m, [m] = 3m\) when \(m\) is odd and \([m] = \dfrac{m}2\) when \(m\) is even. What is \([9]\cdot [6]\) equivalent to?

A. \([81]\)

B. \([54]\)

C. \([37]\)

D. \([27]\)

E. \([18]\)

Answer: D

Source: GMAT Prep

## For all positive integers \(m, [m] = 3m\) when \(m\) is odd and \([m] = \dfrac{m}2\) when \(m\) is even. What is

##### This topic has expert replies

### GMAT/MBA Expert

- [email protected]
- GMAT Instructor
**Posts:**15805**Joined:**08 Dec 2008**Location:**Vancouver, BC**Thanked**: 5254 times**Followed by:**1267 members**GMAT Score:**770

9 is odd, so [9] = (3)(9) = 27

6 is even, so [6] = 6/2 = 3

So, [9] x [6] = 27 x 3 = 81

**BEFORE you select answer choice A**, notice that 81 has brackets around it.

Since 81 is odd, [81] = (3)(81) = 243

So, answer choice A is NOT correct.

So, which of the 5 answer choices equals 81?

Since 27 is odd, [27] = (3)(27) = 81

So, the correct answer is D

Cheers,

Brent