Calculator problem

Algebra Level 2

Note: This problem is incorrect.


I want to calculate the square root of 7 correct to at least 5 decimal places. However, my calculator is dysfunctional and only the green keys work (the red keys do not).

How many key presses are required to display the square root of 7 starting from the All Clear (0) position.

For example, if I wanted to get 0.1 0.1 , then starting from 0, pressing 1 0 x 10^x will give me 1. Pressing 1 0 x 10^x will give me 10 10 . Pressing 1 / x 1/x will give me 0.1 0.1 .


Edit: Sorry. Somebody has pointed out that it can be done in 4 steps using Factorial of Pi. He is right. I was under the impression that the factorial function was defined only for non-negative integers.
Someone else has also pointed a way of doing this with fewer than 9 steps, so the options are not correct.

Anyway, for those still interested, try finding the minimum number of steps needed.

9 12 Impossible
20

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2 solutions

Actually Only four steps are required. ❶ π ❷ n! ❸ int ❹ √

Depends if the factorial accepts non-integer arguments.

Michael Tong - 6 years, 11 months ago

Yes it does.

Aamir Faisal Ansari - 6 years, 11 months ago

but how the answer is 9

g j - 6 years, 11 months ago

One more. ❶ n! ❷ asinh ❸ powten ❹ int ❺ √

Aamir Faisal Ansari - 6 years, 11 months ago
Rohan Jain
Jun 22, 2014

pi * sqr * sqr * log * cube * int * sqrroot

Thanks for sharing how to do it with 7. Can anyone do better?

Calvin Lin Staff - 6 years, 11 months ago

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