Aptitude Hack#68(2-5-19)

Question:

If 137 + 276 = 435 how much is 731 + 672?
A) 534
B) 1403
C) 1623
D) 1513

Answer: C)1623.

Explanation: 

If we try adding the numbers directly (i.e. considering decimal)

    1 
   137
 +276 
  ------  
       3
Since 7+6=13 and the given answer 435 has 5 in the one's place, therefore, the numbers are in base 8;
 Because 13 will correspond to 15 (7+8) in base 8 system.

 Now converting 731 and 672 in decimal
731=> 7x8^2 + 3x8^1 + 1x8^0 = 473 
672=>  6x8^2 + 7x8^1 + 2x8^0 = 442 

Adding 473 + 442 = 915 
Converting 915 into base 8 = 1623.