(mathematics) parity

importance

to investigate, to look up, to look into, to study, to examine, to check up on, to look over / (music) to play, to perform (an instrument) / (music) to tune

important, significant

importance, consequence, significance

a digit (numeral) / a numeral / a figure, a thing expressed as a number (e.g. television viewership, score of games or sales)

sex, gender / (grammar) gender

mathematics (field of study)

occasional

(mathematics) even