Number Series Quiz for IBPS AFO 2026

Solution & Explanation The differences are −1, −2, −3, −4. Thus, 77 − 4 = 73.

Solution & Explanation Pattern: Previous two terms multiplied. 6 × 18 = 108, not 109.

Solution & Explanation Pattern: +7, +26, +63, +124, +215, +342, +511 (Differences are 2^3-1, 3^3-1, 4^3-1, 5^3-1, 6^3-1, 7^3-1, 8^3-1). 128+125=253 is correct, but the sequence of differences shows 253 is the error.

Solution & Explanation Pattern: -4, -8, -12, -16, -20. 251 - 8 = 243.