Simplification practice question for Railways, SSC. Review the correct answer and explanation, then continue with related practice below.
Correct Answerसही उत्तर
B. −14,820
Explanationव्याख्या
We can use the Digital Sum (DS) method to identify the correct option quickly.
Digital sum of 31: 3 + 1 = 4 Therefore: DS of 31³ = DS of 4³ = DS of 64 = 6 + 4 = 10 → 1 Digital sum of 18: 1 + 8 = 9 Therefore: DS of 18³ = DS of 9³ = DS of 729 = 7 + 2 + 9 = 18 → 9 → 0 (mod 9) Digital sum of 37: 3 + 7 = 10 → 1 Therefore: DS of 37³ = 1³ = 1 Digital sum of 210: 2 + 1 + 0 = 3 Hence, overall digital sum: = 1 + 0 − 1 + 3 = 3 Now check option B, −14,820: 1 + 4 + 8 + 2 + 0 = 15 15 → 6 Since the number is negative: −6 ≡ 3 (mod 9) Therefore, option B satisfies the digital-sum check.
For direct verification: 31³ = 29,791 18³ = 5,832 37³ = 50,653 Therefore: 29,791 + 5,832 − 50,653 + 210 = 35,623 − 50,653 + 210 = −15,030 + 210 = −14,820 Hence, the correct answer is −14,820.
सही विकल्प को जल्दी पहचानने के लिए Digital Sum (DS) विधि का उपयोग किया जा सकता है।
अतः सही उत्तर −14,820 है।
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