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Finding a part (practice)
Textbook Part 3, pp. 22–23
GoalFinding-a-part problems; “how much must it increase by?”; working with a calendar.
New words
calendar · taqvimto increase · orttirmoqdate · sana
Explanation
“By how much must 53 increase to make 56?” is also finding a part: 56 − 53 = 3. When counting days on a calendar we also subtract or count back.
Worked examples
18 club members and some parents came to a celebration; 48 badges were handed out: 48 − 18 = 30 parents.
To make 90 from 50 we add 40: 90 − 50 = 40.
Class activity
Class calendar: children count how many days are left until a holiday and write it as a subtraction.
Practice
1
How many must be added to 13 to make 17?
4
2
By how much must 53 increase to make 56?
3
3
Whole 17, one part 10. Other part?
7
4
Find the odd one out: 15 − 5, 20 − 10, 12 − 3
12 − 3 (it gives 9, the others give 10)