For addition: The number 0; that is N + 0 = N for any number N. For multiplication: The number 1; that is, N x 1 = N for any number N.

A process where the measurement of some entity is not obtained by the direct reading of a measuring tool, or by counting of units superimposed alongside or on that entity. For example if the length and width of a rectangle are multiplied to find the area of that rectangle, then the area is an indirect measurement.

The set of numbers: {..., -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6,...}

The points where a line drawn on a rectangular-coordinate-system graph intersect the vertical and horizontal axes.

For addition:

For any number N, its inverse (also called opposite) is a number -N so that N + (-N) = 0 (e.g., the opposite of 5 is -5, the opposite of -3/4 is 3/4).

For multiplication:

For any number N, its inverse (also called reciprocal) is a number N* so that N x (N*) = 1 (e.g., the reciprocal of 5 is 1/5; the reciprocal of -3/4 is -4/3.

An equation of the form y = ax + b, where a and b can be any real number. When the ordered pairs (x, y) that make the equation true for specific assigned values of a and b are graphed, the result is a straight line.