Delta Key Actual Question in XAT 2023
Q. Suppose Haruka has a special key Δ in her calculator called delta key:
Rule 1: If the display shows a one-digit number, pressing delta key Δ replaces the displayed number with twice its value.
Rule 2: If the display shows a two-digit number, pressing delta key Δ replaces the displayed number with the sum of the two digits.
Suppose Haruka enters the value 1 and then presses delta key Δ repeatedly. After pressing the Δ key for 68 times, what will be the displayed number?
- 7
- 4
- 10
- 2
- 8
EXPLANATION
68 = 9(7) + 5
A cycle of 9 presses resets the calculator.
So, pressing it 68 times is equivalent to pressing it 5 times, which generates 7.