cryptarithm
/ˈkrɪptəˌrɪð(ə)m/Mathematics
noun
A mathematical puzzle in which an arithmetical proposition is expressed in letters, each letter standing for one of the ten digits, the task being to find what digit each letter stands for.
Origin
1940s. From crypto- + Greek ἀριθμός number, after either cryptarithmetic or French cryptarithmie. With the formation perhaps compare logarithm.