aritmetik-o = arithmetic. memor-i = to remember.
cent = hundred (142). mil = thousand (142).
erar-o = error, mistake. minut-o = minute.
grad-o = grade, degree. ricev-i = to receive.
kalkul-i = to calculate, to reckon. sekund-o = second.
kiom = how much (140). superjar-o = leap-year.