mathinschool.com
numbers and algebraic expressions
logic, sets, intervals
absolute value
function and its properties
linear function
quadratic function
polynomials
rational function
exponential function
logarithm
number sequences
limits of sequences and functions
derivative and integral of functions
trigonometry
plane geometry
analytic geometry
solid geometry
combinatorics
probability
elements of statistics
kropki game
Number 3 is divisor 12, because 12 divided by 3 give natural number 4. Examples of divisors. Zero has infinity of natural divisors 1, 2, 3, ... Zero is not divisor any natural number. Not allowed divide by zero. Natural number divided by 2 are even numbers: 0, 2, 4, 6, 8, 10, ... and remaining are odd numbers: 1, 3, 5, 7, 9, 11, ...