6
Review: numbers ending in zero
Textbook: Part 1, lesson 6, pp. 19–21
GoalReview multiplying and dividing numbers ending in zero by 10 and 100, and multiplying such numbers by each other.
New words
round number · yaxlit sonzero · nolten · o‘nlikhundred · yuzlik
Explanation
To multiply by 10 we write one zero at the end, to multiply by 100 two zeros. To divide by 10 or 100 we remove that many zeros. To multiply two round numbers, set the zeros aside, multiply the other digits, and put all the zeros back at the end.
Worked examples
50 × 70 = 5 × 7 × 10 × 10 = 35 × 100 = 3500.
800 : 100 = 8; 7 × 100 = 700.
Class activity
“Where did the zeros go?”: the teacher writes 40 × 30. Children use cards to show the steps of removing the zeros and putting them back.
Practice
1
36 × 10 = ?
360
2
4 500 : 100 = ?
45
3
90 × 80 = ?
7200
4
70 × x = 4 200. Find x.
60
5
Each box has 10 flower seedlings. How many seedlings are in 30 boxes?
300