36
Finding an unknown subtrahend
Textbook Part 1, pp. 74–75
GoalFind the number taken away when the starting number and the difference are known.
New words
subtrahend · ayriluvchito check · tekshirmoqstep (pace) · qadam
Explanation
Rule: to find an unknown subtrahend, subtract the difference from the minuend. If 9 − _ = 5, the unknown = 9 − 5 = 4. Check: 9 − 4 = 5 ✓.
Worked examples
10 older pupils gave talks; 4 spoke at the end of the lesson. At the start: 10 − 4 = 6.
Amir was given 8 tasks and 3 are left. Done: 8 − 3 = 5.
Class activity
Pace it out: measure the distance between two children in steps. After one child walks some steps, work out how many steps are still left.
Practice
1
8 − _ = 6
2
2
10 − _ = 3
7
3
Of Dilshod’s 10 friends, 2 are girls. How many are boys?
8
4
Kamron and Anora read 8 lines of a poem. Anora read the last 4. How many did Kamron read?
4