Grade 4
Mathematics
Daily Math Practice
Grade 4
Workbook 3
Rounding & Estimation
Page 1 of 9
Grade 4
Mathematics
Understanding Rounding & Estimation
Rounding makes it easier to work with big numbers and helps to
estimate values in sums.
Example:
Charlie wants to buy a sandwich of R23,00, hot chips of
R17,00 and a Coke of R11,00. He has R60,00 in his wallet.
Will he have enough money to pay for the snacks?
By using Rounding, we can ESTIMATE the total cost of the meal, without adding
the exact amounts together.
Step 1:
Round the amounts off to the nearest TEN:
R23,00 rounded off to the nearest TEN = R20,00
R17,00 rounded off to the nearest TEN = R20,00
R11,00 rounded off to the nearest TEN = R10,00
Step 2:
Add the rounded off amounts together to ESTIMATE the total amount:
R20,00 + R20,00 + R10,00 = R50
Step 3:
Solve the problem by answering the question:
Yes, Charlie will have enough money to pay for the snacks.
To check if our estimation was correct, add the actual amounts together:
R23,00 + R17,00 + R11,00 = R51,00
YES! Our estimation was correct!
Follow these steps for PERFECT ROUNDING:
Example:
Step 1:
Step 2:
Round 1 465 to the nearest Hundred.
Underline the digit to which you should be rounding off:
1 465 Circle the digit directly after the underlined digit.
1 465
Step 3:
Apply rounding rules:
If the circled digit is between 0 and 4, the underlined digit stays the same.
If the circled digit is between 5 and 9, the underlined digit increases by one.
6 is between 5 and 9, therefore 4 will change to 5: 1 500
Don’t forget:
If you have to round off to the nearest HUNDRED, the TENS and UNITS columns will
be zero. If you have to round off to the nearest THOUSAND, the HUNDREDS, TENS and UNITS
columns will be zero.
If you have to round off to the nearest TEN, the UNITS column will be zero.
Page 2 of 9
Grade 4
Mathematics
Day 1: Practice Rounding
Exercise 1:
Round off the following numbers as indicated in the table:
Round off to
Number
Nearest 10
Nearest 100
Nearest 1 000
45
21
203
829
399
1 008
8 917
4 655
2 309
7 777
3 333
6 004
5 967
9 194
3 698
9 504
5 005
8 276
8 999
9 532
Did you see that sometimes a number rounded off to the nearest 10, 100 and
1 000 gives the same answer?
Example: 8 999
Rounded to the nearest 10: 9 in the UNITS column changes the 9 in the TENS
column to a 10. Just as in addition, the one Ten is carried over to the HUNDREDS and
then THOUSANDS column, making the answer 9 000.
Page 3 of 9
Grade 4
Mathematics
Day 2: Practice Rounding
Exercise 1:
In each of the following, round off to the nearest 10.
1.
2.
_______________________
Exercise 2:
1.
Circle the correct answer/s:
Which of the following is the number 3 799 rounded off to the nearest 10?
a) 3 700
2.
b) 510
b) 9 000
b) 2 678
b) 9 498
b) Hundred
c) 8 500
d) 8 600
c) 2 637
d) 2 534
c) 8 509
d) 9 701
c) Thousand
The number 7 010 is the number __________ rounded off to the nearest 10.
a) 7 003
8.
d) 505
The number 6 400 is the number 6 413 rounded to the nearest _______ .
a) Ten
7.
c) 600
The number 9 000 is the number __________ rounded off to the nearest 1 000.
a) 8 312
6.
d) 3 790
The number 2 600 is the number __________ rounded off to the nearest 100.
a) 2 598
5.
c) 3 800
Which of the following is the number 8 507 rounded off to the nearest 1 000?
a) 8 000
4.
b) 3 780
Which of the following is the number 503 rounded off to the nearest 100?
a) 500
3.
______________________
b) 7 000
c) 7 004
d) 7 006
The number 8 100 is the number __________ rounded off to the nearest 100.
a) 8 167
Exercise 3:
b) 8 049
c) 8 050
d) 8 142
Challenging Practice
If a number is rounded off to the nearest 100, the answer is 9 600.
What is the smallest possible original number?
What is the biggest possible original number?
Page 4 of 9
Grade 4
Mathematics
Day 3: Practice Estimation
Exercise 1:
Estimate the lengths indicated by the arrows, by rounding off to the nearest 10:
1.
_______________ cm
2.
__________________ cm
3.
__________________ cm
4.
Add the estimated lengths together:
________________________________________________________________________
________________________________________________________________________
Exercise 2:
Estimate the total length (in centimetres) of Charlie and his friends by rounding off to
the nearest 100:
154 cm
138 cm
158 cm
123 cm
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
Page 5 of 9
Grade 4
Mathematics
Day 4: Operations with Estimation
Exercise 1:
Jason visited Incredible Games. The following electronics were on special:
Kindle:
R2 356,00
1.
Camera:
R1 234,00
Apple watch:
R4 951,00
iPad Mini:
R6 098,00
Games console:
R2 859,00
Estimate the cost of each item as indicated:
Item
Rounded off to
nearest R10
Rounded off to
nearest R100
Rounded off to
nearest R1 000
Kindle
Camera
Apple watch
iPad Mini
Games console
2.
Estimate the costs, rounding off to the nearest R100,00, if Jason wants to buy the following:
a)
Camera and Games Console
3.
a)
b)
Apple watch and Kindle
Estimate the costs, rounding off to the nearest R1 000,00, if Jason wants to buy the following:
iPad Mini and Camera
b)
Games console and Kindle
Page 6 of 9
Grade 4
Mathematics
MEMO: Day 1
Exercise 1:
Round off the following numbers as indicated in the table:
Round off to
Number
Nearest 10
Nearest 100
Nearest 1 000
45
50
21
20
203
200
200
829
830
800
399
400
400
1 008
1 010
1 000
1 000
8 917
8 920
8 900
9 000
4 655
4 660
4 700
5 000
2 309
2 310
2 300
2 000
7 777
7 780
7 800
8 000
3 333
3 330
3 300
3 000
6 004
6 000
6 000
6 000
5 967
5 970
6 000
6 000
9 194
9 190
9 200
9 000
3 698
3 700
3 700
4 000
9 504
9 500
9 500
10 000
5 005
5 010
5 000
5 000
8 276
8 280
8 300
8 000
8 999
9 000
9 000
9 000
9 532
9 530
9 500
10 000
Did you see that sometimes a number rounded off to the nearest 10, 100 and
1 000 gives the same answer?
Example: 8 999
Rounded to the nearest 10: 9 in the UNITS column changes the 9 in the TENS
column to a 10. Just as in addition, the one Ten is carried over to the HUNDREDS and
then THOUSANDS column, making the answer 9 000.
Page 7 of 9
Grade 4
Mathematics
MEMO: Day 2
Exercise 1:
In each of the following, round off to the nearest 10.
1.
2.
20
Exercise 2:
1.
30
Circle the correct answer.
Which of the following is the number 3 799 rounded off to the nearest 10?
a) 3 700
2.
b) 3 780
b) 510
b) 9 000
c) 2 637
b) 9 498
d) 2 534
c) 8 509
d) 9 701
The number 6 400 is the number 6 413 rounded to the nearest _______ .
b) Hundred
c) Thousand
The number 7 010 is the number __________ rounded off to the nearest 10.
a) 7 003
8.
d) 8 600
The number 9 000 is the number __________ rounded off to the nearest 1 000.
a) Ten
7.
c) 8 500
b) 2 678
a) 8 312
6.
d) 505
The number 2 600 is the number __________ rounded off to the nearest 100.
a) 2 598
5.
c) 600
Which of the following is the number 8 507 rounded off to the nearest 1 000?
a) 8 000
4.
d) 3 790
Which of the following is the number 503 rounded off to the nearest 100?
a) 500
3.
c) 3 800
b) 7 000
c) 7 004
d) 7 006
The number 8 100 is the number __________ rounded off to the nearest 100.
a) 8 167
Exercise 3:
b) 8 049
c) 8 050
d) 8 142
Challenging Practice
If a number is rounded off to the nearest 100, the answer is 9 600.
What is the smallest possible original number?
9 550
What is the biggest possible original number?
9 649
9 550
9 600
9 649
Page 8 of 9
Grade 4
Mathematics
MEMO: Day 3
Exercise 2:
Estimate the lengths indicated by the arrows, by rounding off to the nearest 10:
1.
10 cm
2.
20 cm
3.
20 cm
4.
Add the estimated lengths together:
10 cm + 20 cm + 20 cm = 50 cm
Exercise 2:
Estimate the total length (in centimetres) of Charlie and his friends by rounding off to
the nearest 100:
Rounded:
154 cm
138 cm
158 cm
123 cm
150 cm
140 cm
160 cm
120 cm
Total length = 150 cm + 140 cm+ 160 cm + 120 cm = 570 cm
MEMO: Day 4
Exercise 1:
1.
Jason visited Incredible Games. The following electronics were on special:
Estimate the cost of each item as indicated:
Item
Rounded off to
nearest R10
Rounded off to
nearest R100
Rounded off to
nearest R1 000
Kindle
R2 360,00
R2 400,00
R2 000,00
Camera
R1 230,00
R1 200,00
R1 000,00
Apple watch
R4 950,00
R5 000,00
R5 000,00
iPad Mini
R6 100,00
R6 100,00
R6 000,00
Games console
R2 860,00
R2 900,00
R3 000,00
2.
Estimate the costs, rounding off to the nearest R100,00, if Jason wants to buy the following:
a)
Camera and Games Console
b)
R1 200,00 + R2 900,00 = R4 100,00
3.
a)
Apple watch and Kindle
R5 000,00 + R2 400,00 = R7 400,00
Estimate the costs, rounding off to the nearest R1 000,00, if Jason wants to buy the following:
iPad Mini and Camera
R6 000,00 + R1 000,00 = R7 000,00
b)
Games console and Kindle
R3 000,00 + R2 000,00 = R5 000,00
Can you see that rounding off to the nearest R100,00 gives a far more accurate estimation of the
costs than rounding off to R1 000,00?
Page 9 of 9