Lesson 18

“CANCELLATION OF INSIGNIFICANT ZEROS “EASY WAYS IN DIVIDING WHOLE NUMBERS

Objectives

After this lesson, the students are expected to:

divide whole numbers using other method;

perform division of whole numbers mentally;

define “ cancellation of insignificant zeros.”

The cancellation of Insignificant Zeros is one of the easy ways in performing division of whole numbers. It is done by cancelling the insignificant zeros in both the divisor and the dividend.

EXAMPLES:

101

1. 50 5050 505÷5=101 ( both dividend and divisor) -50

050

50

0

210

2. 5 1050 105÷5=21(10) =210 (the insignificant zero in

-10 dividend was cancelled)

50

-50

0

EXAMPLES:

1. 300÷100=3 or 300÷100=3

2. 30 000÷1 000=30

3. 2500÷100=25

To check multiply the quotient to the divisor then multiply also the place value of the removed zeros

Remember that in cancelling both the dividend and divisor, the insignificant zeros are needed to be the same. If you cancelled 3 zeros in the dividend, you need also to cancel 3 zeros from the divisor.

WORKSHEET NO. 18

NAME: ___________________________________ DATE: _____________

YEAR & SECTION: ________________________ RATING: ___________

A. Divide the following using the Cancellation of Insignificant Method.

1. 640÷80=___________________

2. 140÷20=___________________

3. 36000÷600=________________

4. 700÷350=__________________

5. 3500÷70=__________________

6. 350÷ 100=__________________

7. 5600÷ 800=_________________

8. 600÷ 30=___________________

9. 100÷50=____________________

10. 800÷40=___________________

11. 1000÷ 100=_________________

12. 140÷ 70=___________________

13. 420 20=____________________

14. 14000÷ 70=_________________

15. 36000÷180=_________________

16. 4800÷ 240=_________________

17. 99000÷ 330=________________

18. 860÷ 20=___________________

19. 770÷ 770=__________________

20. 630÷ 30=___________________

B. CHALLENGE!!!

1. Copy the figure. Show how to divide it into 2 equal parts. Each part

must have the same size and shape.

2. Copy the figure again. Show how to divide it in 3 equal parts.

3. Copy the figure again. Show how to divide it in 4 equal parts.

Draw a 2 dimensional clock. Then draw a line across the clock so that the sum of the

numbers in each group is the same.

WRITE YOUR SOLUTION HERE: