Englishfor English speakers
estimator
—
noun
(= calculator)
an expert at calculation (or at operating calculating machines)
modulo
Preposition
—
Given a specified modulus of.
21 and 84 are congruent to each other modulo 9, since both numbers leave the same remainder, 3, when divided by 9.
Thus 21 modulo 9 is 3 - because when 21 is divided by 9, the remainder is 3.