58
Adding several numbers in a column
Textbook: Part 2, lesson 56, pp. 32–33
GoalAdd several numbers in a column and in a convenient way.
New words
column · ustunconvenient method · qulay usulpartner (pair to 10 or 100) · jufticarrying · o‘tkazish
Explanation
To add several numbers, write them one under another by place: ones under ones, tens under tens, hundreds under hundreds. Add the ones, carry the tens, then add the tens and the hundreds. Convenient method: first add numbers that make 10 or 100: 430 + 60 + 70 + 40 = 430 + 70 + 60 + 40 = 500 + 100 = 600.
Worked examples
136 + 270 + 124: ones 6 + 0 + 4 = 10, tens 3 + 7 + 2 + 1 = 13, hundreds 1 + 2 + 1 + 1 = 5. The answer is 530.
229 + 71 + 206 + 94: 229 + 71 = 300 and 206 + 94 = 300, so the total is 600.
Class activity
“Find the partner”: write numbers on the board (229, 71, 206, 94, 150). Children find pairs whose sum is a round number and mark them in the same colour.
Practice
1
136 + 270 + 124 = ?
530
2
437 + 128 + 281 = ?
846
3
In a convenient way: 430 + 60 + 70 + 40 = ?
600
4
260 l of water was used for trees, 270 l for bushes and 350 l for the garden. How many litres in total?
880