How much space, in cubic units, is left vacant when maximum number of 5x5x5 cubes are fitted in a rectangular box measuring 10x15x18 ?  Choose the correct answer:
A) 50
B) 150
C) 250
D) 350
E) 450
No of cubes that can be accommodated in box = (10*15*18)/(5*5*5)   15*10 in numerator can be perfectly divided by 5*5 in denominator.   side with length 18 can't be perfectly divided by 5 and hence is the limiting factor. Closet multiple of 5 less that 18 is 15. so vacant area in cube =   =15*10*(18-15)   =15*10*3= 
<gadget id="calculator">15*10*3</gadget>
<output>450</output>
450   Ans - 450
<result>E</result>
How much space, in cubic units, is left vacant when maximum number of 5x5x5 cubes are fitted in a rectangular box measuring 10x15x18 ?