ABSTRACT
Spanish numerals are simple and regular, although this makes the three unexpected forms, quinientos 500 (not *cinco cientos), setecientos 700 (not *sietecientos) and novecientos 900 (not *nuevecientos) easy to forget. Remember also that 16-29 are rather arbitrarily written as one word (dieciséis, veintidós, etc.) whereas other tens plus units, i.e. 31-99, are joined by y: treinta y uno, ochenta y seis, etc.
