ARITHMETIC.

ARTICLE 1. ARITHMETIC is the science of numbers, and the art of computing by them.

2. A Unit is one.

3. A Number is a unit, or a combination of units.

4. A Concrete, or Denominate Number, is a number in which the kind of unit is expressed; as, one boy, two apples, three slate pencils, four sounds.

5. An Abstract Number is a number in which the kind of unit is not expressed; as, one, two, three.

6. EXERCISE.

Name the concrete numbers in the following list:

Four girls; seven swans; two; ten; nine chairs; five knives; eight; twelve horses; six mules; two oxen; four; eleven; seven pond lilies; one; ten; thirteen ; nine days; fifteen lessons; two rabbits;

bushels.

Name the abstract numbers in the above.

six

7. The fundamental operations of written Arithmetic are based upon NOTATION, and consist of ADDITION, SUBTRACTION, MULTIPLICATION, and DIVISION.

NOTATION AND NUMERATION.

8. Notation is the art of writing numbers. Numeration is the art of reading numbers.

9. Besides being expressed in words, numbers are repre