What will come at the place of question mark ? 6, 11, 21, 36, 56, ?

Question: What will come at the place of question mark ?6, 11, 21, 36, 56, ?Solution: 11 - 6 = 521 - 10 = 1036 - 21 = 1556 - 36 = 20The difference increases by 5 each time.∴ The next difference should be 20 + 5 = 25⇒ 56 + 25 = 81Shortcut: 6 (+5)→ 11 (+10)→ 21 (+15)→ 36 (+20)→ 56 (+25) → 81.