25
Dividing round numbers
Textbook: Part 1, lesson 25, pp. 78–80
GoalLearn how to divide round numbers; multiplication and division as inverse operations.
New words
dividend · bo‘linuvchidivisor · bo‘luvchiquotient · bo‘linmainverse operation · teskari amal
Explanation
To divide round numbers, strike out the same number of zeros from the end of both numbers and divide what is left: 15 000 : 500 = 150 : 5 = 30. If the divisor has no zeros, read the dividend in place units and use the table: 4 900 : 7 = 49 hundreds : 7 = 7 hundreds = 700. We check division by multiplying.
Worked examples
64 000 : 800 = 640 : 8 = 80. Check: 80 × 800 = 64 000.
5 600 : 8 = 700, because 56 : 8 = 7 and 7 hundreds = 700.
Class activity
“With and without zeros”: the teacher writes a division problem; children cross out the zeros, solve the simpler problem and check by multiplying.
Practice
1
420 : 6 = ?
70
2
350 000 : 7 000 = ?
50
3
48 000 : 400 = ?
120
4
4 500 000 so‘m is made of notes of 50 000 so‘m. How many notes are there?
90
5
A rectangle has area 540 000 cm² and length 900 cm. What is its width in cm?
600