A frame with small balls which slide along wires. It is used as a tool or toy for counting.
In plane Cartesian coordinates, the x-coordinate of a point: its position from the origin (y axis) measured parallel to the x-axis.
Exactly equal to 1⁄640 of a square mile, about 4,046 m2.
Put numbers or amounts together to get a total. The signal is “+”.
An addend number which is involved in addition. Numbersbeing added are considered to be the addends.
The process of adding two or more numbers together to find their total. 1+1=2, 5+8=13.
additive identity 加法恒等元,加法单位元
When added to any element x in the set, yields x. Usually the sum of the number x and 0 yields the same number.
additive inverse 加性逆元
The opposite of a number. For example, the additive inverse of 12 is -12.
adjacent angles 邻角
Two angles are adjacent when they have a common side and a common vertex (corner point), and don’t overlap.
adjoint matrix 伴随矩阵
The adjoint of a square matrix A, is the transpose of the matrix of cofactors of A.