If $ means 'divided by'; @ means 'multiplied by'; # means 'minus', then the value of 10#5@1$5 is

(a) 0
(b) 1
(c) 2
(d) 9 ✓ UPSC's answer

Why the answer is (d)

• The expression is 10#5@1$5, where # means minus, @ means multiplied by, and $ means divided by.

• Substituting the standard operators, the expression becomes 10 - 5 * 1 / 5.

• According to the order of operations (BODMAS/PEMDAS), division and multiplication are performed before subtraction.

• First, calculate 5 * 1, which equals 5.

• Next, divide that result by 5: 5 / 5 = 1.

• Finally, subtract this result from 10: 10 - 1 = 9, which corresponds to option (d).

Why the other options are wrong

(a) 0: Option (a) is incorrect because the final result of the calculation is 9, not 0.
(b) 1: Option (b) is incorrect because it represents the intermediate result of the division step (5/5) rather than the final answer after subtraction.
(c) 2: Option (c) is incorrect because the final result of the calculation is 9, not 2.

Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2019, held on 2 June 2019. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.