Table of contents |
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Getting started |
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Exercise 1.1 |
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Exercise 1.2 |
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Check your progress |
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Q1: What is the value of the digit 9 in these numbers?
(a) 809.46
Ans: 9 ones
(b) 2021.89
Ans: 9 hundredths
(c)123 456.95
Ans: 9 tenths
Q2: write these numbers in words and digits
(a) 200 000 + 5000 + 400 + 8 + 0.9
Ans: two hundred and five thousand, four hundred and eight point nine (205 408.9)
(b) 500 000 + 70 000 + 30 + 6 + 0.01
Ans: five hundred and seventy thousand thirty six point zero one (570 036.01)
Q3: (a) What number is ten times bigger than 0.01?
Ans: 0.1
(b) What number is one hundred times smaller than 555?
Ans: 5.55
Q4: What is the missing number?
100 x 10 = 10 000 ÷
Ans: 10
Q5: Round these lengths to the nearest whole number.
(a) 6.2 m
Ans: 66m
(b) 36.5 cm
Ans: 376m
(c) 12.3 m
Ans: 12m
(d) 10.6 cm
Ans: 11m
Q6: A number with 1 decimal place is rounded to the nearest whole number.
(a) What is the smallest number that rounds to 100?
Ans: 99.5
(b) What is the largest number that rounds to 10?
Ans: 10.4
Q1: What is the value of the digit 7 in these numbers?
(a) 6703.46
Ans: 7 hundred
(b) 213.807
Ans: 7 thousandths
(c) 456.702
Ans: 7 tenths
(d) 60.078
Ans: 7 hundredths
Q2: Sonia has these five cards.What is the smallest number, greater than 1, she can make usina all her cards?
Ans: 2.046
Q3: Find the odd one out.
Explain your answer.
Ans: Odd one out is 12.34. All the others are equivalent to 1.234.
Q4: Add these numbers together and write the total number in words and digits.
(a) 2 + 0.1 + 0.03 + 0.009
Ans: two point one three nine (2.139)
(b) -900-9-0.9-0.009
Ans: negative nine hundred and nine point nine zero nine (−909.909)
(c) 20 + 5 + 0.4 + 0.03 + 0.001
Ans: twenty-five point four three one (25.431)
(d) -3-0.4-0.08-0.001
Ans: negative three point four eight one (-3.481)
Swap books with your partner and check their answer.
Read the numbers to each other
Q5: Copy and complete.
37.844 = 30 + 7 + + 0.04 +
Ans: 0.8 or 8/10 and 0.004 or 4/1000
Q6: Petra is regrouping decimal numbers. She spills ink on her work.
What number is under each ink blot?
(a) 0.546 = 0.4 ++0.006
Ans: 0.14
(b) 0.789 - 0.7 + 0.07 +
Ans: 0.019
Q7: Find the missing numbers.
(a) 7.2 x 1000 =
Ans: 7200
(b) 0.85 x 100 =
Ans: 85
(c) 4.28 x 10 =
Ans: 42.8
(d) 670 ÷ 100 =
Ans: 6.7
(e) 151 ÷ 1000 =
Ans: 0.151
(f) 5.5 ÷ 10 =
Ans: 0.55
Q8: Look at these number cards.Write the letter of the card that is:
(a) one thousand times bigger than 12
Ans: C
(b) one hundredth of 12
Ans: D
(c) one thousandth of 120 000
Ans: E
Q9: Mira divides a number by 10, then by 10 again and then by 10 again.
Her answer is 0.005
What number did she start with?
Ans: 5
Q1: Round these decimals to the nearest whole number.
4.09 7.89 2.55 7.45
Ans: 4 8 3 7
Q2: Leo bought a book costing $14.65.What is the cost of the book to the nearest dollar?
Ans: $15
Q3: Which of these numbers rounds to 5 when rounded to the nearest whole number?
4.35 4.05 4.5 5.05 4.55 5.35 5.5 5.53
Check your answers to questions 1 to 3 with your partner.
Ans: 4.5 5.05 4.55 5.35
Q4: Round these numbers to the nearest tenth.
4.52 7.81 2.35 9.07
Ans: 4.5 7.8 2.4 9.1
Q5: Which of these numbers rounds to 7.5 when rounded to the nearest tenth?
7.35 7.05 7. 51 7.55 7.49 7.56 7.53
Check your answers to questions 4 and 5 with your partner.
Ans: 7.51 7.49 7.53
Q6: Correct all the statements that are false.
(A) 3.04 is 3 when rounded to the nearest whole number and the nearest tenth.
Ans: False, 3.04 is 3.0 when rounded to the nearest tenth
(B) 5.03 is 5 when rounded to the nearest whole number and 5.0 when rounded to the nearest tenth.
Ans: True
(C) 6.95 is 7 when rounded to the nearest whole number and 6.9 when rounded to the nearest tenth.
Ans: False, 6.95 is 7.0 when rounded to the nearest tenth.
Discuss your answers with your partner.
Make sure you explain the reasons you have given.
Q7: Round these measures to the nearest tenth.
55.55 litres 12.22 metres 35.45 kilograms
Ans: 55.6 litres 12.2 metres 35.5 kilograms
Q8: Choose the smallest number from this list that rounds to
1. 0.55 0.99 1.9 1.45 0.5 1.05 0
Ans: 0.5
Q9: Jasper says, ‘7.97 is 8 when rounded to the nearest whole number and is also 8 when rounded to the nearest tenth
Is Jasper correct?
Explain your answer.
Ans: 7.97 is 8 when rounded to the nearest whole number. 7.97 is 8.0 when rounded to the nearest tenth.
The 7 in the hundredths place increases the tenths by one so 7.9 becomes 8.0.
If the number is rounded to the nearest tenth, there must be a digit in the tenths place, even if it is zero.
Think like a mathematician
Q1: The sides of a rectangle are measured in centimetres to 2 decimal places using a micrometer (an instrument for measuring length accurately).
Ans: 5 cm is between 4.50 and 5.49 cm
Q2: The measurements are rounded to the nearest whole number. They are 5 cm and 6 cm.
Ans: 6 cm is between 5.50 and 6.49 cm
Q3: What is the smallest possible perimeter of the rectangle?
Ans: Smallest possible perimeter = 4.50 + 4.50 + 5.50 +5.50 = 20.00 cm
Q1: Copy and complete.
87.655 = 80 + 7 + +
+
Ans: 0.6 + 0.05 + 0.005
Q2: What decimal number is represented by
Ans: 97.314
Q3: How many times bigger is the value of the digit 6 in 64.53 than the value of the digit 6 in 0.367?
Ans: 1000
Q4: (a) What is 3.08 rounded to the nearest tenth?
Ans: 3.1
(b) What is 9.55 rounded to the nearest whole number?
Ans: 10
Q5: Find the missing numbers.
(a) x 0.9 = 9
Ans: 10
(b) 705 ÷ = 7.05
Ans: 100
(c) x 0.16 = 160
Ans: 1000
(d) 34 ÷ 1000 =
Ans: 0.034
Q6: The announcer said, ‘Ingrid won the 100 metre race in 13.9 seconds.’ Her time was originally measured to 2 decimal places.
What was the slowest time she could have run?
Ans: 13.94 second
63 docs|17 tests
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5. How can understanding the number system help in real-life applications? | ![]() |