11
Adding up to a round number (31 + 9)
Textbook: Part 1, lesson 11, pp. 24–25
GoalLearn the case where the ones add up to a whole ten (31 + 9).
New words
round number (whole tens) · yaxlit sonfilling up to a ten · o‘nlikka to‘ldirishstork · laylakone · birlik
Explanation
We calculate 31 + 9 with place-value units: 3 tens 1 one + 9 ones = 3 tens 10 ones. 10 ones make 1 ten, so we get 4 tens, that is 40. When the ones make 10, the answer is a round number.
Worked examples
62 + 8: 2 + 8 = 10, so 6 tens and 1 more ten = 70.
37 + 3 = 40; 41 + 9 = 50; 53 + 7 = 60.
Class activity
“Fill up to ten”: the teacher says numbers like 24, 35, 48 and children raise a hand and say which number must be added to reach the next whole ten.
Practice
1
41 + 9 = ?
50
2
53 + 7 = ?
60
3
75 + 5 = ?
80
4
Dilnoza drew 6 storks and Malika drew 4 more than her. How many did they draw together?
16