Trick:

No need to do CALCULATIONS. Just observe two things. Firstly, SOMETHING is being subtracted from 78 which means answer would be less than 78. Secondly, we have to check WHETHER the term in the brackets is negative or POSITIVE. It would be negative if1.95 × 9.998 would be greater than 24.98 which is not true. Hence number would be less than 78 and only option 58 is less than 78. Option 1 is the right answer.

Detailed solution:

It can be approximated as 78 – [5 + 3 of (25 – 2 × 10)],

Now using BODMAS rule

Follow BODMAS rule to solve this question, as PER the order given below,

Step-1: Parts of an equation enclosed in 'Brackets' must be solved first, and in the bracket,

Step-2: Any mathematical 'Of' or 'Exponent' must be solved next,

Step-3: Next, the parts of the equation that contain 'Division' and 'Multiplication' are calculated,

Step-4: Last but not least, the parts of the equation that contain 'Addition' and 'Subtraction' should be calculated.

⇒ 78 – [5 + 3 of (25 – 20)], (Simplifying ‘multiplication’ 2 × 10 = 20)

⇒ 78 – [5 + 3 of 5], (Simplifying ‘subtraction’ 25 – 20 = 5)

⇒ 78 – [5 + 3 × 5], (Simplifying ‘of’)

⇒ 78 – [5 + 15], (Simplifying ‘multiplication’ 3 × 5 = 15)

⇒ 78 – 20, (Simplifying ‘addition’ 5 + 15 = 20)

⇒ 58, (Simplifying ‘subtraction’ 78 – 20 = 58)

∴ its approximated value is 58