SBI PO – 2015 – 27

SIMPLIFICATION  

Q. 12 × 3.5 – 8.5 × 3.2 =?

(1) 14.8      (2) 18.4       (3) 69.2       (4) 16.8       (5) None of these

 

Detailed explanation: 

12 × 3.5 – 8.5 × 3.2 =?  

Or, 6 × 7 – 17 × 1.6 =? 

Or, ? = 42 – 27.2 = 14.8 Ans.

Explanation: 12 × 3.5 = 6 × (2 × 3.5) = 6 × 7                                                              

Similarly, 8.5 × 3.2 = (8.5 × 2) × 1.6 = 17 × 1.6                                       

Also, 17 ×1.6 = 17 × (1 + 0.6) = 17 + 10.2 = 27.2                                  

[Note: When 5 occurs at the unit place, it is to be doubled, so as to get '0' at the unit place and the number becomes easy to multiply]