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Q1. Sonu's mother needed screws of different sizes. This teaches us that measuring small differences requires:
Answer: A — The story shows that standard units are too large for precise measurements, so we divide 1 cm into 10 tenths to measure accurately.
Q2. How many one-tenths are there in 27/10?
Answer: C — 27/10 means 27 one-tenths, since each 1/10 is one one-tenth.
Q3. Read the measurement 3 5/10 cm aloud:
Answer: B — A mixed number like 3 5/10 is read as 'three and five one-tenths' or 'three and five-tenths.'
Q4. Which represents the smallest length?
Answer: B — 3/100 is much smaller than 3/10 because hundredths are 10 times smaller than tenths.
Q5. A paper sheet measures 8 9/10 units. When folded in half, its length falls between which two tenths?
Answer: B — Half of 8 9/10 is 4 45/100, which lies between 4 4/10 (=4 40/100) and 4 5/10 (=4 50/100).
Q6. Shylaja's hand length is 12 4/10 units and palm length is 6 7/10 units. What is her middle finger length? (Hint: Subtract palm from hand length.)
Answer: A — 12 4/10 − 6 7/10: Cannot subtract 7/10 from 4/10, so borrow 1 unit to get 11 14/10 − 6 7/10 = 5 7/10.
Q7. In the place value system, if ones place has value 1, tenths place has value:
Answer: A — Each place to the right is 1/10 of the previous place, so tenths = 1/10 of ones place.
Q8. A Celestial Pearl Danio is 2 4/10 cm long and a Philippine Goby is 9/10 cm long. How much longer is the Danio?
Answer: A — 2 4/10 − 9/10 = 1 14/10 − 9/10 = 1 5/10 cm. (Converting 2 4/10 to 1 14/10 by borrowing 1 unit.)
Q9. When adding 15 3/10 4/100 and 2 6/10 8/100, why do we group units, tenths, and hundredths separately?
Answer: B — Just as we add ones with ones and tens with tens in whole numbers, we add hundredths with hundredths, tenths with tenths, and units with units in decimals.
Q10. If we split a one-tenth into 10 equal parts, what fraction of the unit is each part?
Answer: B — One-tenth divided into 10 parts means 1/10 ÷ 10 = 1/100 of the unit.
How many one-tenths make 1 unit?
10 one-tenths equal 1 unit.
What does 2 7/10 cm mean?
2 cm and 7 one-tenths of a cm, or 27/10 cm total.
How many one-hundredths are in 1 one-tenth?
10 one-hundredths make 1 one-tenth.
Write 45 one-hundredths in two other ways.
45/100 can be written as 4 5/10 (converting 40/100 to tenths) or 0 45/100.
Why do we split units into 10 parts instead of other numbers?
Because 10 is the base of our Indian place value system, making calculations consistent and easy.
If Sonu's lower arm is 2 7/10 units and upper arm is 3 6/10 units, what is the total?
Total is 6 3/10 units: (2+3) units and (7+6) tenths = 5 13/10 = 6 3/10.
Read 15 3/10 4/100 aloud.
Fifteen and three-tenths and four-hundredths, or fifteen and thirty-four-hundredths.
When subtracting 6 7/10 from 12 4/10, why do we need to borrow?
Because we cannot subtract 7 tenths from 4 tenths, so we borrow 1 unit (= 10 tenths) first.
How many one-hundredths equal 1 unit?
100 one-hundredths equal 1 unit.
Convert 34/10 into mixed number form.
34/10 = 3 4/10 (three and four-tenths).
What is the length of the Sonu's arm if his lower arm is 2 7/10 units and upper arm is 3 6/10 units? Write your answer as a mixed number. [1 mark]
Add units separately from tenths. If tenths exceed 10, convert 10 tenths to 1 unit.
A pencil is 7 8/10 units long. A sharpener is 2 3/10 units long. Find the total length of both objects. Show your working. [2 marks]
Add the units together and add the tenths together separately. Remember, 10 tenths = 1 unit.
Shylaja's total hand length is 12 4/10 units. Her palm measures 6 7/10 units. Calculate the length of her middle finger by subtracting palm from hand length. Show all steps, including borrowing if needed. [3 marks]
Cannot subtract 7/10 from 4/10 directly. Borrow 1 unit (convert to 10/10) from the whole number part first. Then subtract tenths from tenths and units from units.
A honeybee has three body parts: Head = 2 3/10 units, Thorax = 5 4/10 units, and Abdomen = 7 5/10 units. (a) Find the total length of the honeybee. (b) If a fly is 15 8/10 units long, how much longer is the fly than the honeybee? Show all working and explain each step. [5 marks]
(a) Add all three parts by grouping units and tenths separately. Watch for tenths that sum to 10 or more and convert to units. (b) Subtract the honeybee's total from the fly's length; borrow if the tenths part of honeybee is larger than fly's tenths.
Q1. Assertion (A):
To measure the length of a screw accurately when the measurement falls between 2 cm and 3 cm, we need to divide the unit into smaller parts like tenths.
Reason (R):
Whole unit measurements cannot capture precise values that lie between whole numbers.
Answer: A — Both A and R are true, and R is the correct explanation of A — Both the assertion and reason are true. The reason correctly explains why the assertion is true: we need smaller units (tenths) specifically because measurements often fall between whole units, and whole units alone cannot represent these intermediate values precisely.
Q2. Assertion (A):
The length 3 4/10 units is the same as 34/10 units.
Reason (R):
Because 3 units equal 30 tenths, and 4/10 tenths can be added to get 34/10 tenths.
Answer: B — Both A and R are true, but R is NOT the correct explanation of A — The assertion is true: 3 4/10 = 30/10 + 4/10 = 34/10. The reason is also technically true (3 = 30/10 and adding 4/10 gives 34/10), but it explains the conversion through basic arithmetic rather than explaining why they represent the same length. Both are correct, but the reason isn't the most direct explanation.
Q3. Assertion (A):
When subtracting 6 7/10 from 12 4/10, we must regroup because 4 tenths is less than 7 tenths.
Reason (R):
Regrouping in subtraction is only necessary when the digit in the units place of the minuend is smaller than the digit in the units place of the subtrahend.
Answer: C — A is true but R is false — The assertion is true—we must regroup because we cannot subtract 7 from 4 in the tenths place. However, the reason is false because it only mentions the units place, not the fractional (tenths) place where the actual problem occurs. The reason focuses on the wrong place value.
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Case Study:
Ravi is building a model house and needs to measure the dimensions of different wooden pieces. He has a ruler marked with tenths of a centimeter. The door frame length is 15 7/10 cm, the window frame length is 8 4/10 cm, and the roof piece length is 12 6/10 cm. Ravi needs to check if he has enough wood by calculating the total length of these three pieces. He also needs to find how much longer the roof piece is compared to the window frame.
Q1. What is the total length of the three wooden pieces?
Answer: B
Q2. How much longer is the roof piece than the window frame?
Answer: B
Q3. If Ravi wants to add another piece that is 5 8/10 cm long, what will be the new total?
Answer: D
Q4. Which two pieces have a combined length closest to 24 cm?
Answer: D
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