A Glossary of Mathematical Terms - D
Decagon
A ten-sided polygon.
Decimal
Decimals are numbers with decimal points.
Decimal fraction
A fraction whose denominator is a power of 10.
Denominator
See Fraction
Diagonal
In polygons: a segment connecting two non consecutive vertices.
Difference
See Subtraction.
Digit
Digits are the symbols used to write numerals in a number system: in the usual (base10) system they are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.
Dilation (Dilatation)
A geometric transformation where figures are enlarged or reduced.
Discount
A percentage subtracted from a number.
Disjoint sets
Sets that have non common elements.
Distributive property
A property that links two operations (e.g. addition and multiplication betwen numbers: a(b+c)=ab+ac).
Dividend
See Division
Divisibility rules
Patterns that allow us to determine wheter or not a number divides evenly into another number, without actually doing the division.
Division
6 divided by 2: 6/2;
the quotient of 6 and 2 is 3: 6/2=3
the ratio of 6 to 2 is 3: 6/2=3;
the outcome of the division is the quotient;
the first term is the dividend;
the second term is the divisor.
Divisor
See Division and Factor.
Dodecagon (Duodecagon)
A twelve-sided polygon.