The Masoretes never read or translated Greek. But the total of Hebrew letters (Aramaic uses the same alphabet as Hebrew) is 39,613.

The Masoretes (ba'alei hamasorah, בעלי המסורה)

They recorded an indexing system. When a word occurs for the first time in the Hebrew text, especially if it is spelled unusually, the Masoretes listed every occurrence of that spelling, so that manuscripts could be checked against this written index.

Tiberian niqqud (נִיקוּד טְבֵרִיָנִי‎ Nikkud Tveriyani) is a system of diacritics devised by the Masoretes of Tiberias around 750 CE to 950 CE. It is the only existing vocalization system for Hebrew. The other two, the Eretz Yisrael system and Babylonian system are long since extinct.

Though already possessing copies in Greek from the LXX (from around 300 B.C.), and having scrolls written by the Masoretes from 900 A.D., the oldest extant copies in Hebrew were discovered in 1948 having been written 1,000 or more years prior as part of the Library of Qumran and found in the caves of the Dead Sea.