GATE 2014 EC (EC1) – Question 5

General Aptitude · Quantitative Aptitude: Arithmetic and Number Computation · 1 mark · Numerical answer

Find the next number: 12, 35, 81, 173, 357, ______.

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Show answer and explanation

Correct answer: 725 to 725

Explanation

Each term is twice the preceding term plus11:2×12+11=35,2×35+11=81,2×81+11=173 and2×173+11=357. Applying the same rule gives2×357+11=**725**. Equivalently the successive differences23,46,92,184 double.