40
Dividing a sum by a number
Textbook: Part 2, lesson 40, pp. 4–6
GoalLearn to divide a sum by a number: divide each addend, then add the quotients.
New words
sum · yig‘indiaddend · qo‘shiluvchiquotient · bo‘linmaconvenient method · qulay usul
Explanation
A sum can be divided by a number in two ways: find the sum first and divide, or divide each addend separately and add the results. (35 + 21) : 7 = 35 : 7 + 21 : 7 = 5 + 3 = 8. Check: 56 : 7 = 8. The second way is handy when each addend divides exactly.
Worked examples
(40 + 24) : 8 = 40 : 8 + 24 : 8 = 5 + 3 = 8.
(600 + 900) : 3 = 600 : 3 + 900 : 3 = 200 + 300 = 500.
Class activity
“Two ways”: in pairs, one child adds first and then divides, the other divides each addend separately. They compare results and say which way was easier.
Practice
1
(28 + 56) : 7 = ?
12
2
(120 + 180) : 6 = ?
50
3
13 girls and 11 boys are playing in the yard. They split into 3 equal teams. How many children are in each team?
8
4
A farmer packed 450 kg of apples and 150 kg of pears equally into 6 identical crates. How many kg of fruit are in each crate?
100