Bear in mind though, that the steam market takes 15% tax, and keys go for about 2.45 on the SCM whereas bp.tf values them at about 2.

For the sake of convenience I will do these calculations in dollars:

the most recent sale was $44.87

44.87 x 0.85= 38.1395

38.1395/ 2.45 = 15.6

If I did the math correctly, thats only about 15.6 keys. + 1 key pure is 16.6