How to translate "The stolen letter of Arithmetic"

Question

I would like to give a memorable title to a short text that I am writing and I thought of the above one in reference to the short novel by E. A. Poe, The Purloined Letter.

A few attempts with automatic translation tools gave me mediocre results and my Latin is unfortunately very rusty. I would really appreciate if someone could help me with this translation.

Nb.: the capitalized word "Arithmetic" refers to the field of mathematics studying numbers and is thus intended as a noun, not an adjective.

Answer 1

This is a relatively simple answer, only requiring three (or four) words, the nouns epistola and arithmētica, and the perfect passive participle of the verb surripiō, surreptus. All combined together, you get the following phrase:

Epistola surrepta Arithmēticae

If you want to be fancy, arithmētica is a Greek loanword and can thus be declined using its Greek declension, utilizing the genitive -ēs ending instead of the standard -ae.

Epistola surrepta Arithmēticēs

In addition, if the word the is emphatic in your English title, you might want to consider using the weak demonstrative adjective, like so:

Ea epistola surrepta Arithmēticae (-ēs)

As is with Latin, you can rearrange the word order to your personal preference; I am simply following your original order for the sake of simplicity.