rounding
DESCRIPTION
Rounding. 621.8 19.02 57.04 98.63 1.03 610.8 519.6. 622 19 57 99 1 611 520. Round to the nearest whole number. 19.023 57.046 81.774 89.522 1.03 2.59 49.97. 19.0 57.0 81.8 89.5 1.0 2.6 50.0. Round to one decimal place. 1.902 5.704 0.1036 2.974 0.006 3.899 0.003. - PowerPoint PPT PresentationTRANSCRIPT
Rounding
Round to the nearest whole number
• 621.8• 19.02• 57.04• 98.63• 1.03• 610.8• 519.6
• 622• 19• 57• 99• 1• 611• 520
Round to one decimal place
• 19.023• 57.046• 81.774• 89.522• 1.03• 2.59• 49.97
• 19.0• 57.0• 81.8• 89.5• 1.0• 2.6• 50.0
Round to two decimal places
• 1.902• 5.704• 0.1036• 2.974• 0.006• 3.899• 0.003
• 1.90• 5.70• 0.10• 2.97• 0.01• 3.90• 0.00
The reading 4.1 kg, has two significant figures.
The width of the footpath is 1.81m (to the nearest cm)
The width of the footpath is 1.81m (to the nearest cm)
How many significant figures?
Complete this table
Rounded width Significant Figures
1.81
2
1
Complete this table
Rounded width Significant Figures
1.81 3
1.8 2
2 1
Round to one significant figure
• 7.56• 2.7• 4.6• 10.6
• 8• 3• 5• 10
How many significant figures?
• 9.6• 2.5• 55.1• 1.26• 22.4• 178.3• 8.75• 3.24
• 2• 2• 3• 3• 3• 4• 3• 3
How many significant figures?
• 46.81• 3.808• 4.077• 71.08• 83.881• 778.049
• 4• 4• 4• 4• 5• 6
How many significant figures?
• 400.00• 40.0• 1.4• 1.40• 1.400• 10.0• 1.50• 100.00
• 5• 3• 2• 3• 4• 3• 3• 5
• The length of this pencil is 83 mm to the nearest mm.
• 83 mm has been rounded to two significant figures.
• 83 mm = 0.083 m• 0.083 m also has two
significant figures.
How many significant figures?
• 0.061• 0.007• 0.00061• 0.46• 0.070• 0.0700• 0.0074• 0.07006
• 2• 1• 2• 2• 2• 3• 2• 4
Exercise 9
Rounding
Round the lengths of N. Z. Rivers to the nearest 10 Km.
• Waikato• Clutha• Wanganui• Taieri• Rangitiki• Waitaki
• 425• 322• 290• 288• 241• 209
Round the lengths of N. Z. Rivers to the nearest 10 Km.
• Waikato• Clutha• Wanganui• Taieri• Rangitiki• Waitaki
• 425 = 430• 322 = 320• 290 = 290• 288 = 290• 241 = 240• 209 = 210
Round the heights of N. Z. Mountains to the nearest 100 m.
• Cook• Tasman• Ruapehu• Taranaki• Ngauruhoe• Tongariro
• 3764• 3498• 2797• 2518• 2291• 1968
Round the heights of N. Z. Mountains to the nearest 100 m.
• Cook• Tasman• Ruapehu• Taranaki• Ngauruhoe• Tongariro
• 3764 = 3800• 3498 = 3500• 2797 = 2800• 2518 = 2500• 2291 = 2300• 1968 = 2000
Round the areas of N. Z. Lakes to the nearest 1000 ha.
• Taupo• Te Anau• Wakatipu• Wanaka• Manapouri• Hawea
• 60 606• 34 447• 29 267• 19 166• 14 245• 11 914
Round the areas of N. Z. Lakes to the nearest 1000 ha.
• Taupo• Te Anau• Wakatipu• Wanaka• Manapouri• Hawea
• 60 606 = 61 000• 34 447 = 34 000• 29 267 = 29 000• 19 166 = 19 000• 14 245 = 14 000• 11 914 = 12 000
Round the areas of N. Z. Regions correct to 2 significant figures.
• Northland
• Auckland
• Waikato
• Bay of Plenty
• Gisborne
• Hawkes' Bay
• Taranaki
• Manawatu - Wanganui
• Wellington
• 13 941
• 5 600
• 25 598
• 12 447
• 8 351
• 14 164
• 7 273
• 22 215
• 8 124
Round the areas of N. Z. Regions correct to 2 significant figures.
• Northland
• Auckland
• Waikato
• Bay of Plenty
• Gisborne
• Hawkes' Bay
• Taranaki
• Manawatu - Wanganui
• Wellington
• 13 941 = 14 000
• 5 600 = 5 600
• 25 598 = 26 000
• 12 447 = 12 000
• 8 351 = 8 400
• 14 164 = 14 000
• 7 273 = 7 300
• 22 215 = 22 000
• 8 124 = 8 100
Round the population of N. Z. Regions correct to 3 significant figures.
• Nelson• Tasman• Marlborough• West Coast• Canterbury• Otago• Southland• New Zealand
• 40 279• 37 973• 38 397• 32 512• 468 040• 185 083• 97 100• 3 618 302
Round the population of N. Z. Regions correct to 3 significant figures.
• Nelson• Tasman• Marlborough• West Coast• Canterbury• Otago• Southland• New Zealand
• 40 279 = 40 300• 37 973 = 38 000• 38 397 = 38 400• 32 512 = 32 500• 468 040 = 468 000• 185 083 = 185 000• 97 100 = 97 100• 3 618 302 = 3 620 000
This table shows the population of Auckland's 4 cities rounded to the nearest 1000.
Copy down and complete the table.
City Population Min. Pop Max. Pop
North Shore 172 000 171 500 172 499
Waitakere 156 000
Auckland 346 000
Manukau 254 000
This table shows the population of Auckland's 4 cities rounded to the nearest 1000.
Copy down and complete the table.
City Population Min. Pop Max. Pop
North Shore 172 000 171 500 172 499
Waitakere 156 000 155 500 156 499
Auckland 346 000 345 500 346 499
Manukau 254 000 253 500 254 499
Exercise 10
Approximate Calculations
Oral examples - 1
• a. 90 x 6• b. 90 x 60• c. 900 x 60• d. 900 x 600
• 540• 5400• 54 000• 540 000
Oral examples - 2
• a. 80 x 5 • b. 80 x 50 • c. 800 x 50 • d. 800 x 500
• 400• 4000• 40 000• 400 000
Oral examples - 3
= 50
Oral examples - 3
= 50
Oral examples - 3
= 500
Oral examples - 3
= 500
Oral examples - 4
= 200
Oral examples - 4
= 200
Oral examples - 4
= 2000
Oral examples - 4
= 2000
Written examples
1. 80 x 7
2. 80 x 70
3. 800 x 70
4. 800 x700
• 560• 5600• 56 000• 560 000
Written examples
5. 40 x 5
6. 40 x 50
7. 400 x 50
8. 400 x 500
• 200• 2000• 20 000• 200 000
9.
= 50
10.
= 50
11.
= 500
12.
= 500
13.
= 200
14.
= 20
15.
= 2000
16.
= 2000
Estimation
Answers are not exact
Exercise 10
17. 91 x 18 18. 82 x 2919. 73 x 36 20. 64 x 4721. 621 x 1922. 685 x 3223. 817 x 38 24. 893 x 51
• 90 x 20 ≈ 1800• 80 x 30 ≈ 2400• 70 x 40 ≈ 2800• 60 x 50 ≈ 3000• 600 x 20 ≈ 12000• 600 x 30 ≈ 18000• 800 x 40 ≈ 32000• 900 x 50 ≈ 45000
25.
≈ 5
26.
≈ 2
27.
≈ 4
28.
≈ 3
29.
≈ 40
30.
≈ 30
31.
≈ 20
32.
≈ 50
33.
≈ 400
34.
≈ 2500
35.
≈ 90 000
36.
≈ 160 000
37.
≈ 10
38.
≈ 20
39.
≈ 30
40.
≈ 100
41.
≈ 40
42.
≈ 20
43.
≈ 60
44.
≈ 30
45.
≈ 2
46.
= 4
47.
= 6
48.
= 3
49.
= 8000
50.
= 27000
51.
= 160000
52.
= 810000
Making Estimates
Continued
Fill the gaps
Item Unit cost ($)
Quantity Estimated cost ($)
Apples 1.83 4
Chickens 8.95 9
Calculator 16.85 7
DVD 9.95 10
Fill the gaps
Item Unit cost ($)
Quantity Estimated cost ($)
Apples 1.83 4 8
Chickens 8.95 9 81
Calculator 16.85 7 140
DVD 9.95 10 100
Fill the gaps
Item Unit cost ($)
Quantity Estimated cost ($)
Hairdryer 23.15 38
Toaster 47.95 27
Shorts 14.85 74
Chairs 83.75 65
Fill the gaps
Item Unit cost ($)
Quantity Estimated cost ($)
Hairdryer 23.15 38 800
Toaster 47.95 27 1500
Shorts 14.85 74 700
Chairs 83.75 65 5600
Fill the gaps
Item Total cost Quantity Estimated unit cost
Shorts 64.91 7
Books 47.99 8
Heaters 3385 9
Fridges 6725 7
Fill the gaps
Item Total cost Quantity Estimated unit cost
Shorts 64.91 7 9
Books 47.99 8 6
Heaters 3385 9 400
Fridges 6725 7 1000
Fill the gaps
Item Total cost Quantity Estimated unit cost
Watches 2225 51
Shoes 4309 78
Calculator 2683 92
Trousers 3416 83
Fill the gaps
Item Total cost Quantity Estimated unit cost
Watches 2225 51 40
Shoes 4309 78 50
Calculator 2683 92 30
Trousers 3416 83 40
Exercise 12
1.
= 2
2.
= 3
3.
= 10
4.
= 100
5.
= 2
6.
= 10
7.
= 2
8.
= 2
9.
= 4
10.
= 8
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.