- Hebrew numerals 15 and 16 are non-standard to avoid resemblance to the Holy Name
- There could be alternative Hebrew numerals for hundreds, 500 through 900, based on final forms of letters
- Greek and Slavonic numerals can be both in the lower and upper case
- Greek numeral for 6 is sigma-tau ligature which resembles by shape an obsolete letter vau or digamma; it can also be written as two separate letters sigma and tau
- Greek numeral for 90 is qoppa (an obsolete letter)
- Greek numeral for 900 is sampi (an obsolete letter)
- Slavonic numerals for 6, 90 and 900 are letters which are not present in the Greek alphabet
- The match between Hebrew and Greek/Slavonic numerals breaks at 90 (Hebrew qoph=100, Greek qoppa=90) and thereafter. This is because there is no Greek letter corresponding to tsade: it was dropped from the alphabet when Greeks received it from the Phoenicians
- Hebrew year is obtained by adding 3760 to A.D.
- Christian year "from the creation of the world" is obtained by adding 5508 to A.D.