This scale is in one sense wholly vigesimal, and in another way it is not to be regarded as pure, but as mixed.  Below 20 it is quinary, and, however far it might be extended, this quinary element would remain, making the scale quinary-vigesimal.  But in another sense, also, the Aino system is not pure.  In any unmixed vigesimal scale the word for 400 must be a simple word, and that number must be taken as the vigesimal unit corresponding to 100 in the decimal scale.  But the Ainos have no simple numeral word for any number above 20, forming all higher numbers by combinations through one or more of the processes of addition, subtraction, and multiplication.  The only number above 20 which is used as a unit is 200, which is expressed merely as 10 twenties.  Any even number of hundreds, or any number of thousands, is then indicated as being so many times 10 twenties; and the odd hundreds are so many times 10 twenties, plus 5 twenties more.  This scale is an excellent example of the cumbersome methods used by uncivilized races in extending their number systems beyond the ordinary needs of daily life.

In Central Asia a single vigesimal scale comes to light in the following fragment of the Leptscha scale, of the Himalaya region:[354]

    10. kati.
    40. kafali = 4 x 10,
          or kha nat = 2 x 20.
    50. kafano = 5 x 10,
          or kha nat sa kati = 2 x 20 + 10.
   100. gjo, or kat.

Further to the south, among the Dravidian races, the vigesimal element is also found.  The following will suffice to illustrate the number systems of these dialects, which, as far as the material at hand shows, are different from each other only in minor particulars: 

  MUNDARI.[355]

    10. gelea.
    20. mi hisi.
    30. mi hisi gelea = 20 + 10.
    40. bar hisi = 2 x 20.
    60. api hisi = 3 x 20.
    80. upun hisi = 4 x 20.
   100. mone hisi = 5 x 20.

In the Nicobar Islands of the Indian Ocean a well-developed example of vigesimal numeration is found.  The inhabitants of these islands are so low in the scale of civilization that a definite numeral system of any kind is a source of some surprise.  Their neighbours, the Andaman Islanders, it will be remembered, have but two numerals at their command; their intelligence does not seem in any way inferior to that of the Nicobar tribes, and one is at a loss to account for the superior development of the number sense in the case of the latter.  The intercourse of the coast tribes with traders might furnish an explanation of the difficulty were it not for the fact that the numeration of the inland tribes is quite as well developed as that of the coast tribes; and as the former never come in contact with traders and never engage in barter of any kind except in the most limited way, the conclusion seems inevitable that this is merely one of the phenomena of mental development among savage races for which we have at present no adequate explanation.  The principal numerals of the inland and of the coast tribes are:[356]