146
Dividing round numbers
Textbook: Part 4, lesson 136, pp. 44–45
GoalDivide round numbers by thinking in tens.
New words
dividend · bo‘linuvchidivisor · bo‘luvchiquotient · bo‘linmaten · o‘nlik
Explanation
To divide round numbers we think in tens: 60 : 3 = 6 tens : 3 = 2 tens = 20. If the divisor is round too: 150 : 30 = 15 tens : 3 tens = 5. We check by multiplying: 5 × 30 = 150.
Worked examples
240 : 40 = 24 tens : 4 tens = 6.
If x × 3 = 240, then x = 240 : 3 = 80.
Class activity
“With tens”: the teacher shows ten-sticks. 120 : 40 – “group 12 sticks into fours” – children count the groups and find the answer 3.
Practice
1
60 : 3 = ?
20
2
150 : 30 = ?
5
3
240 : 40 = ?
6
4
420 : 70 = ?
6
5
x × 3 = 240, x = ?
80
6
60 bars of soap came to a shop and were packed equally into 3 boxes. How many bars are in one box?
20