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.

Hundred : Hundred refers to the number 100.

Hundreds digit : The hundreds digit is the third digit left of the decimal point. It counts multiples of hundred.

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.

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.

Consecutive numbers : Two integers are consecutive if you get the second integer by adding 1 to the first integer.

Factor : If a natural number is divisible by a second natural number, that second natural number is called a factor of the first natural number. For example the factors of 12 are 1,2,3,4,6 and 12.

Geometric progression : A sequence of numbers $x_1, x_2, x_3,\ldots$ is called geometric progression if the quotient between any two consecutive numbers in the sequence is the same. $1,2,4,8,\ldots$ and $2,6,18,54,\ldots$ are examples of geometric progressions.