irreducible fraction
fully simplified fraction
unit fraction
rational number written as a fraction where the numerator is one and the denominator is a positive integer
billionth
reciprocal of 1,000,000,000
thousandth
one of a thousand equal parts of a whole
quantum number
notation for conserved quantities in physics and chemistry
billionth
reciprocal of a billion (short scale) or of one thousand million (long scale)