STANDARD ARITHMETIC. NOTATION AND NUMERATION. 1. A single thing is called a Unit. 2. A unit or a collection of units is a Number. A number answers the question "how many?" A number may be expressed by words or other characters, 3. The method of expressing numbers by figures or let- The method of expressing numbers by figures is called the Arabic The method of expressing numbers by letters is called the Roman 4. The method of reading numbers expressed by figures THE ARABIC SYSTEM. 5. In counting a large number of objects, it is natural to 6. The Arabic system of notation, which is a decimal 0 1 2 3 4 5 6 7 8 9 By combining these figures in accordance with certain When figures are written side by side, the one at the right expresses units, the next tens, and the next 9. Figures in units' place express units of the first order; those in tens' place, units of the second order; those in hun- dreds' place, units of the third order; etc. 10. The units of the second order, or tens, are named ten, The suffix ty means ten. Thus forty means four tens. 11. The numbers between 1 ten and 2 tens are named Thirteen means three and ten; fourteen, four and ten, etc. 12. The other numbers between 20 and 100 are read with- Thus, 35 is read thirty-five, not thirty and five. Three units of the second order, five of the first order. Five units of the second order, seven of the first order. Seven units of the first order, nine of the second order. Write all numbers below twenty. Write all numbers between twenty and forty. Write all numbers between fifty and seventy. 14. In reading numbers expressed by three figures, the tens are read after the hundreds, and the units after the tens, without the word and. Thus, 346 is read three hundred forty-six. Five units of the third order, two of the second, three of the first. Two units of the third order, two of the second, two of the first. Four units of the third order, four of the second, four of the first. 16. From the previous examples the following general principle is deduced: PRINCIPLE. The representative value of a figure is increased ten-fold by each removal one place to the left, and decreased ten-fold by each removal one place to the right. |