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

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.

Subtraction : Subtraction is the mathematical operation that describes decreasing a number by an amount equal to a second number. The mathematical symbol for subtraction is the minus sign $-.$ The term subtraction is also used for a generalization of this basic operation on numbers to functions, vectors and matrices.

Ten : Ten refers to the number $10.$

Tens digit : The tens digit is the second digit left of the decimal point. For example 31.2 and 32 both have tens digits equal to 3.

Hour : A unit for measuring time equal to 60 minutes.

Minute : A minute is a unit for measuring time equal to $\frac{1}{60}$ of an hour or 60 seconds.

Negative : A number is negative if it is $\lt 0.$

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

Positive : Positive means $\geq 0.$