70 or 72?

Luke 10:1.

Metzger tells us the external evidence is almost evenly divided.

And if we ask about the symbolism, interestingly, the number of the nations in Genesis 11 is 70 but in the Septuagint (the LXX, the Greek Translation of the Old Testament) there are 72.

Metzger, "Seventy or Seventy-two Disciples?" in Historical and Literary Studies, Pagan, Jewish and Christian (Leiden and Grand Rapids, 1968) pp67-76 lists about 20 instances of the use of 70 or 72 in ancient Jewish literature.

There are lots of 70s in the OT:
The souls in the house of Jacob
Moses 70 elders (Ex 24:1, 9; Num 11:16f, 24f), sons and priests
70 year events

72 appears only once in Numbers 31:38, where 72 cattle are set aside for sacrificial offering.

According to a late rabbinic tradition, Moses' commandments were heard in 70 languages (b. Sab. 88b, The Alphabet of Rabbi Akiva).

The Sanhedrin had 70 members when the High Priest isn't included (m. Sanh. 1:5-6).

72 also in the Letter of Aristeas 46-50 (72 translators of LXX) and in 3 Enoch 17.8; 18.2-3; 30.2 (72 princes and kings in the world).

72 is therefore by far the more difficult reading and scholars prefer it!

Bock opts for the originality of 72 but thinks it has no symbolism.