My grandma has an old Felix artithmometer. AFAIK these are capable of the same things as the Curta but with a less elegant and convenient form factor. It really

My grandma has an old Felix artithmometer. AFAIK these are capable of the same things as the Curta but with a less elegant and convenient form factor. It really shows why Curtas are so valuable. Last time I visited her I used it to estimate sqrt(2) to 3 digits precision. (Result is on the left side https://imgur.com/a/CoEuC https://imgur.com/a/CoEuC)