ITBS Math Concepts and Estimation 1 — Questions and Answers
Question 1: Which of the following is the best estimate for 48 × 21?
- 800
- 1,000 (Correct answer)
- 1,200
- 1,500
Correct answer: 1,000
Rounding 48 to 50 and 21 to 20 gives 50 × 20 = 1,000, which is the closest estimate.
Question 2: What is the value of the digit 7 in the number 3,742?
- 7
- 70
- 700 (Correct answer)
- 7,000
Correct answer: 700
The digit 7 is in the hundreds place, so its value is 700.
Question 3: A rectangle has a length of 12 cm and a width of 5 cm. What is its area?
- 34 cm²
- 60 cm² (Correct answer)
- 17 cm²
- 70 cm²
Correct answer: 60 cm²
Area of a rectangle = length × width = 12 × 5 = 60 cm².
Question 4: Which number is between 3/4 and 1 on a number line?
- 1/2
- 7/8 (Correct answer)
- 2/3
- 1/4
Correct answer: 7/8
7/8 = 0.875, which falls between 3/4 (0.75) and 1 (1.0).
Question 5: If a bag of apples weighs about 3.7 pounds, which is the best estimate of the total weight of 6 bags?
- 18 pounds
- 22 pounds (Correct answer)
- 24 pounds
- 30 pounds
Correct answer: 22 pounds
Rounding 3.7 to 4 gives 4 × 6 = 24, but the actual answer 3.7 × 6 = 22.2 is closest to 22 pounds.
Question 6: What is the least common multiple (LCM) of 4 and 6?
- 2
- 12 (Correct answer)
- 18
- 24
Correct answer: 12
The smallest number divisible by both 4 and 6 is 12 (4×3 = 12, 6×2 = 12).
Question 7: A store sells notebooks for $2.95 each. About how much would 8 notebooks cost?
- $16
- $20
- $24 (Correct answer)
- $28
Correct answer: $24
Rounding $2.95 to $3 and multiplying by 8 gives $24, which is the best estimate.
ITBS Math Concepts and Estimation 1
Which of the following is the best estimate for 48 × 21?