To complete this lesson, complete the following tasks:

1. Study the lesson for mastery.

2. Memorize the lesson that it may be recited.

3. Complete the lesson assessment.

## Lesson

1. How do we express numbers between 10 and 20, 20 and 30, etc.?

**The numbers between 10 and 20, 20 and 30, etc., are expressed by representing the tens and units of which they are composed.**

2. What do we call one ten and one unit?

**One ten and one unit are called “eleven”.**

3. How is one ten and one unit written?

**One ten and one unit is written 11.**

4. What do we call one ten and two units?

**One ten and two units are called “twelve”.**

5. How is one ten and two units written?

**One ten and two units is written 12.**

6. What do we call one ten and three units?

**One ten and three units are called “thirteen”.**

7. How is one ten and three units written?

**One ten and three units is written 13.**

8. What do we call one ten and four units?

**One ten and four units are called “fourteen”.**

9. How is one ten and four units written?

**One ten and four units is written 14.**

10. What do we call one ten and five units?

**One ten and five units are called “fifteen”.**

11. How is one ten and five units written?

**One ten and five units is written 15.**

12. What do we call one ten and six units?

**One ten and six units are called “sixteen”.**

13. How is one ten and six units written?

**One ten and six units is written 16.**

14. What do we call one ten and seven units?

**One ten and seven units are called “seventeen”.**

15. How is one ten and seven units written?

**One ten and seven units is written 17.**

16. What do we call one ten and eight units?

**One ten and eight units are called “eighteen”.**

17. How is one ten and eight units written?

**One ten and eight units is written 18.**

18. What do we call one ten and nine units?

**One ten and nine units are called “nineteen”.**

19. How is one ten and nine units written?

**One ten and nine units is written 19.**

20. What do we call two tens and one unit?

**Two tens and one unit are called “twenty-one”.**

21. How is two tens and one unit written?

**Two tens and one unit is written 21.**

22. What do we call two tens and two units?

**Two tens and two units are called “twenty-two”.**

23. How is two tens and two units written?

**Two tens and two units is written 22.**

## Assessment

**Modern Arithmetic III, Article 05 Exam**