Three of the sides of a rectangular prism have areas of 91, 39, and 21. What is the volume of the rectangular prism?
Select:
A) 252
B) 269
C) 273
D) 920
E) 1911
One easy way to get the answer for this question is just multiply the unit's digits of these three numbers, i.e (1*9*1 = 9) (Why the multiplication is needed?, you can see the solution suggested by Bunuel in the above post)   Now look out for the answer whose square gives us a 9 in the unit place.   So, it is easy to pic (273) 273 whose square will give us a 9 in the unit place( 3*3), and hence this is the answer.
<result>C</result>
Three of the sides of a rectangular prism have areas of 91, 39, and 21. What is the volume of the rectangular prism?