A shopkeeper sells two notebooks for the same selling price. He gains 10% on one and loses 10% on the other. What is the net result?

The verified answer is 2.0% Loss, option C. Apply the profit or loss multiplier to cost price: SP = CP(1 ± rate/100). The question-specific working supplied in the record is: When gain% and loss% are equal and SP is same, Net Loss% = (x/10)^2. Net Loss = (10/10)^2 = 1.0%.. Profit and loss questions become unreliable when a percentage is applied to the wrong base. Profit or loss percent uses cost price, while discount percent uses marked price. If several changes occur, convert each change into a multiplier and apply them in order. The distractors 0% Loss, 1.0% Loss, 3.0% Loss can result from interchanging cost price and selling price, treating discount as loss, adding successive rates, ignoring quantity, or rounding before the final step. A dependable check is to assume cost price 100 whenever only percentages are involved, reconstruct the selling value, and compare the resulting ratio with the selected option. Also verify direction: profit requires selling price above cost price, whereas loss requires it below cost price. This method preserves the numerical relationships in the stem and develops formula selection, percentage-base recognition and option elimination for SSC, Railway, Banking and other competitive aptitude examinations.