Q1: Estimate the product of 23 × 47 by rounding both numbers to the nearest ten. (a) 1000 (b) 1200 (c) 900 (d) 1100
Solution:
Ans: (a) 1000 Explanation: Round 23 to the nearest ten = 20. Round 47 to the nearest ten = 50. Then multiply: \(20 \times 50 = 1000\). This gives us an estimated product of 1000.
Q2: Which is the best estimate for 38 × 52? (a) 1500 (b) 2000 (c) 2500 (d) 1800
Solution:
Ans: (b) 2000 Explanation: Round 38 to the nearest ten = 40. Round 52 to the nearest ten = 50. Then multiply: \(40 \times 50 = 2000\). The best estimate is 2000.
Q3: Estimate 72 × 19 by rounding to the nearest ten. (a) 1400 (b) 1200 (c) 1600 (d) 1000
Solution:
Ans: (a) 1400 Explanation: Round 72 to the nearest ten = 70. Round 19 to the nearest ten = 20. Then multiply: \(70 \times 20 = 1400\). The estimated product is 1400.
Q4: Which pair of rounded numbers would you use to estimate 56 × 34? (a) 50 × 30 (b) 60 × 40 (c) 60 × 30 (d) 50 × 40
Solution:
Ans: (c) 60 × 30 Explanation: When rounding to the nearest ten, 56 rounds to 60 and 34 rounds to 30. Therefore, the correct pair for estimation is \(60 \times 30\).
Q5: Estimate the product of 84 × 27 using rounding. (a) 2400 (b) 2100 (c) 2700 (d) 1800
Solution:
Ans: (a) 2400 Explanation: Round 84 to the nearest ten = 80. Round 27 to the nearest ten = 30. Then multiply: \(80 \times 30 = 2400\). The estimated product is 2400.
Q6: Which estimate is closest to the actual product of 41 × 62? (a) 2000 (b) 2400 (c) 3000 (d) 1800
Solution:
Ans: (b) 2400 Explanation: Round 41 to the nearest ten = 40. Round 62 to the nearest ten = 60. Then multiply: \(40 \times 60 = 2400\). This is the closest estimate to the actual product.
Q7: Estimate 68 × 15 by rounding both numbers to the nearest ten. (a) 1200 (b) 1000 (c) 1400 (d) 900
Solution:
Ans: (c) 1400 Explanation: Round 68 to the nearest ten = 70. Round 15 to the nearest ten = 20. Then multiply: \(70 \times 20 = 1400\). The estimated product is 1400.
Q8: What is a reasonable estimate for 92 × 48? (a) 4500 (b) 5000 (c) 4000 (d) 3600
Solution:
Ans: (a) 4500 Explanation: Round 92 to the nearest ten = 90. Round 48 to the nearest ten = 50. Then multiply: \(90 \times 50 = 4500\). A reasonable estimate is 4500.
## Section B: Fill in the Blanks Q9: To estimate the product of two 2-digit numbers, we round each number to the nearest __________ before multiplying.
Solution:
Ans: ten Explanation: When estimating products of 2-digit numbers in Grade 4, we use rounding to the nearest ten to make multiplication easier.
Q10: When estimating 35 × 42, we round 35 to __________ and 42 to 40.
Solution:
Ans: 40 Explanation: The number 35 rounds to 40 when rounding to the nearest ten, since 35 is exactly halfway and we round up.
Q11: The estimated product of 20 × 60 is __________.
Solution:
Ans: 1200 Explanation: Multiplying \(20 \times 60 = 1200\). This is a basic multiplication fact using multiples of 10.
Q12: To estimate 77 × 31, round 77 to 80 and 31 to __________.
Solution:
Ans: 30 Explanation: When rounding 31 to the nearest ten, it becomes 30 because 31 is closer to 30 than to 40.
Q13: An estimate helps us find an answer that is __________ to the exact answer.
Solution:
Ans: close Explanation: An estimate gives us an approximate answer that is close to the actual value, making it easier to check if our exact answer is reasonable.
Q14: The product of 50 × 70 is __________.
Solution:
Ans: 3500 Explanation: Multiplying \(50 \times 70 = 3500\). This uses the pattern of multiplying multiples of 10: \(5 \times 7 = 35\), then add two zeros.
## Section C: Word Problems Q15: A school library has 28 shelves. Each shelf holds 43 books. Estimate the total number of books in the library by rounding to the nearest ten.
Solution:
Ans: Step 1: Round 28 to the nearest ten = 30 Step 2: Round 43 to the nearest ten = 40 Step 3: Multiply: \(30 \times 40 = 1200\) Final Answer: About 1200 books
Q16: A farmer plants 52 rows of corn. Each row has 38 corn plants. Estimate how many corn plants the farmer has in total.
Solution:
Ans: Step 1: Round 52 to the nearest ten = 50 Step 2: Round 38 to the nearest ten = 40 Step 3: Multiply: \(50 \times 40 = 2000\) Final Answer: About 2000 corn plants
Q17: Each box of crayons contains 64 crayons. A teacher orders 21 boxes for her classroom. Estimate the total number of crayons she will receive.
Solution:
Ans: Step 1: Round 64 to the nearest ten = 60 Step 2: Round 21 to the nearest ten = 20 Step 3: Multiply: \(60 \times 20 = 1200\) Final Answer: About 1200 crayons
Q18: A bakery makes 79 cookies each day. Estimate how many cookies they make in 32 days.
Solution:
Ans: Step 1: Round 79 to the nearest ten = 80 Step 2: Round 32 to the nearest ten = 30 Step 3: Multiply: \(80 \times 30 = 2400\) Final Answer: About 2400 cookies
Q19: A train has 48 cars. Each car can hold 67 passengers. Estimate the total number of passengers the train can hold.
Solution:
Ans: Step 1: Round 48 to the nearest ten = 50 Step 2: Round 67 to the nearest ten = 70 Step 3: Multiply: \(50 \times 70 = 3500\) Final Answer: About 3500 passengers
Q20: A toy store sells 83 board games each week. Estimate how many board games they sell in 26 weeks.
Solution:
Ans: Step 1: Round 83 to the nearest ten = 80 Step 2: Round 26 to the nearest ten = 30 Step 3: Multiply: \(80 \times 30 = 2400\) Final Answer: About 2400 board games
The document Worksheet (with Solutions): Estimate Products (2-Digit Numbers) is a part of the Grade 4 Course Math Grade 4.
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