35
Finding an unknown minuend
Textbook Part 1, pp. 72–73
GoalFind the starting number (minuend) when the subtrahend and difference are known.
New words
minuend · kamayuvchisubtrahend · ayriluvchidifference · ayirmaat first · dastlab
Explanation
Rule: to find an unknown minuend, add the subtrahend to the difference. If _ − 4 = 6, the unknown = 6 + 4 = 10. Check: 10 − 4 = 6 ✓. In other words: what went away plus what was left gives what there was at first.
Worked examples
3 apples were picked from a tree and 5 were left. At first the tree had 5 + 3 = 8 apples.
A farmer took 8 sacks of carrots to the shop and kept 2 at home. Harvest: 8 + 2 = 10 sacks.
Class activity
Children get a “left” card and a “went away” card. They put them together to find the “there were” number.
Practice
1
_ − 3 = 4
7
2
_ − 5 = 5
10
3
A farmer had some chicks. 2 ran away and 7 were left. How many chicks were there?
9
4
A shepherd took out 10 sheep. 4 are in the shade. How many are in the sun?
6