The first Christians knew and quoted the Septuagint (LXX), the Greek translation of the Hebrew scriptures.
It is clearly shown that the first Christians, authors of the New Testament, quoted the LXX over 90% of the time. (See the chart halfway down this page). This is a strong indicator that Jews in the time of Christ knew the LXX just as well (perhaps better) than the original Hebrew Bible.
This is a curiosity. The very first Christians were Jews. Their mother tongue was Hebrew, a close cousin to Aramaic. It was the Hebrew Bible that was recited at the temple. They would have memorized the Hebrew Bible in synagogue school.
The Jews had also learned another language, the language of the entire civilized world--Greek.
Bowed over their writing desks, seventy scribes are paused. They listen intently for the next phrase to be spoken. At the front of the room, the head scribe holds an open scroll covered in Hebrew and Aramaic. He reads aloud the next phrase in Hebrew, then mentally translates it and speaks it again--in Greek. The 70 scribes quickly write what they have heard.This is the story of the Septuagint, as I heard it. It doesn't mesh exactly with the facts, but it makes for a good legend.
300 years before Christ, Alexander the Great--a Greek--had conquered nations from Egypt to India. He brought with him Greek culture and the Greek language. His conquest shrank the world. Greek language allowed any people from different nations and languages to communicate.
Naturally, the Hebrew Bible (known to Christians as the Old Testament or OT today) was also translated into Greek. The story goes that 70 (or 72) scribes worked on the translation, thus the name "Septuagint" which means 70, and the abbreviation LXX, which is the Roman numeral for 70.
"The New Testament writers weren’t nitwits or dishonest. They were using the Septuagint." http://blog.logos.com/2007/12/why_use_the_septuagint/