Count : To count means to find out the number of objects by adding one for every object.

Addition : Addition is the mathematical operation that describes increasing a number by an amount equal to a second number. The mathematical symbol for addition is the plus sign $+.$ The term addition is also used for a generalization of this basic operation on numbers to functions, vectors and matrices.

Ones digit : The first digit left of the decimal point (or the digit furthest to the right if there is no decimal point). It counts multiples of 1.

Ten : Ten refers to the number $10.$

Count : To count means to find out the number of objects by adding one for every object.

Number : A number $x$ is a mathematical symbol representing a quantity.