| One ten and three units are thirteen | 13 |
| One ten and four units are fourteen | 14 |
| One ten and five units are fifteen | 15 |
| One ten and six units are sixteen | 16 |
| One ten and seven units are seventeen | 17 |
| One ten and eight units are eighteen | 18 |
| One ten and nine units are nineteen | 19 |
| Two tens are twenty | 20 |
| Two tens and one unit are twenty-one | 21 |
| Two ones and five units are twenty-five | 25 |
| Three tens are thirty | 30 |
| Four tens are forty | 40 |
| Five tens are fifty | 50 |
| Six tens are sixty | 60 |
| Seven tens are seventy | 70 |
| Eight tens are eighty | 80 |
| Nine tens are ninety | 90 |
§ 3. The numbers from 20 to 30, and from 30 to 40, &c., may be expressed by writing the tens and the units of which they are composed.
The number twenty-six is composed of two tens and six units; and is expressed by writing 2 in the place of the tens and six in the place of the units, thus:—26.
Ninety-seven has 9 tens and seven units; written 97.
§ 4. Ten tens are one hundred.
The one is written in the third place from the right hand, which is the hundreds place, and the places of the units and ten are filled by naughts, thus:—100.
The mode of writing one unit and two units, one ten and two tens, &c., has been explained.
§ 5. In writing one hundred, two hundred, &c., write the figure representing the hundreds in the third place, and fill the places of the units and the tens with naughts; thus:—
| Two hundred | 200 |
| Three hundred | 300 |
| Four hundred | 400 |
| Five hundred | 500 |
