Rules of Approximation: 1. If a number has digits to the right of the decimal less than 5, then just drop the digits to the right of the decimal. The number so obtained will be the approximated value. 2. If a number has digits to the right of the decimal more than 5, then just drop the digits to the right of the decimal and raise the remaining number by '1'.The number so obtained will be the approximated value. Concept: In this type of question, we are expected to calculate approximate value (not exact value), so we can replace the given numbers by their nearest perfect places which makes the calculation easy. {(255.8 × 15.84)1/3 × √(3.2 × 7.8 ÷ 5.7)} ÷ (2 × 3.14 + 25.69 – 22.25) = ? ÷ 100 Taking approximate value, we get {(256 × 16)1/3 × √(3 × 8 ÷ 6)} ÷ (2 × 3 + 26 – 22) = ? ÷ 100 Follow BODMAS rule to solve this question, as per the order given below, Calculation: Since we need to find out the approximate value, we can write these values to their nearest integers. Taking approximate value, we get {(256 × 16)1/3 × √(3 × 8 ÷ 6)} ÷ (2 × 3 + 26 – 22) = ? ÷ 100 ⇒ (16 × 16 × 16)1/3 × √4 ÷ (6 + 4) = ? ÷ 100 ⇒ 16 × 2 ÷ 10 = ? ÷ 100 ⇒ 16 × (1/5) = ? ÷ 100 ⇒ ? = 320 ∴The approximate value of question mark (?) in the following question is 320.