# McGraw Hill My Math Grade 5 Chapter 2 Lesson 8 Answer Key Estimate Products

All the solutions provided in McGraw Hill Math Grade 5 Answer Key PDF Chapter 2 Lesson 8 Estimate Products will give you a clear idea of the concepts.

## McGraw-Hill My Math Grade 5 Answer Key Chapter 2 Lesson 8 Estimate Products

Math in My World

Example 1
A pet store has 12 gecko lizards for sale. Each gecko lizard costs $92. About how much money would the store make if it sells all 12 gecko lizards? Estimate the product of 92 and 12. One Way Round one factor. THINK It is easier to compute 92 × 10 than 90 × 12. By rounding one factor, the estimate is ____ Another Way Round both factors. By rounding both factors, the estimate is ____. Answer: By rounding one factor, the estimate is 920 By rounding both factors, the estimate is 900. Another Way Use compatible numbers. By using compatible numbers, the estimate is _____ Use a calculator to multiply 92 × 12. What do you get? ____ Answer: By using compatible numbers, the estimate is 9000. Use a calculator to multiply 92 × 12. The answer is 1104. Circle whether the estimates were all less than or greater than the actual product. less than greater than the estimate is 920 is less than the actual product. the estimate is 900 is less than the actual product. Guided Practice Estimate by rounding or using compatible numbers. Show how you estimated. Question 1. Round both factors. The product is about ____ Answer: The product is about 600 Explanation: Talk Math Show two different ways you could estimate 312 × 18. Question 2. Use compatible numbers. The product is about ____ Answer: The product is about 8000. Explanation: Independent Practice Estimate by rounding. Show how you estimated. Question 3. Answer: 1308 The estimation by rounding is 1300. Explanation: Given multiplicand is 218 and the multiplier is 6. By multiplying the both multiplicand 937 and multiplier 6, we get the value as 1308. Question 4. Answer: 476. The estimation by rounding the number is 480. Explanation: Given multiplicand is 68 and the multiplier is 7. By multiplying both multiplicand 68 and multiplier 7, we get the value 476. Question 5. Answer: 3799 The estimation by rounding the answer is 3800. Explanation: First, start with units first. So multiply 9 by 1. Then move on to the tens digit. So multiply 9 by 3. Next move on to hundreds place then multiply 9 by 1. Next, repeat the same with number 2. By multiplying both multiplicand 131 and multiplier 29, we get the value 3799. Question 6. 61 × 68 ≈ ___ Answer: 4148 The estimation by rounding the answer is 4150. Explanation: First, start with units first. So multiply 8 by 1. Then move on to the tens digit. So multiply 8 by 6. Continue the same process with digit 6. By multiplying both multiplicand 61 and multiplier 68, we get the value 4148. Question 7. 79 × 56 ≈ ___ Answer: 4424 The estimation by rounding the answer is 4420. Explanation: By multiplying both multiplicand 79 and multiplier 56, we get the value 4424. Question 8. 392 × 46 ≈ ___ Answer: 18032 The estimation by rounding the answer is 18030. Explanation: By multiplying both multiplicand 392 and multiplier 46, we get the value 18032. Estimate by using compatible numbers. Show how you estimated. Question 9. Answer: The multiplication of the given number is 5512. The estimated answer is 5500. Explanation: Now use compatible numbers That is 110 × 50 Then the answer is 5500. Question 10. Answer: 198 The estimated answer by using compatible numbers is 200. Explanation: Now use compatible numbers That is 30 × 6 Then the answer is 180. Question 11. Answer: 1016 The estimated answer is 1100. Explanation: Question 12. 33 × 84 ≈ ___ Answer: 2772. Explanation: By multiplying both multiplicand 33 and multiplier 84, we get the value 2772. Question 13. 450 × 21 ≈ ___ Answer: 9450 Explanation: By multiplying both multiplicand 33 and multiplier 84, we get the value 2772. Question 14. 729 × 42 ≈ ___ Answer: 30618 Explanation: By multiplying both multiplicand 729 and multiplier 42, we get the value 30618. Problem Solving Question 15. The table shows the number of pounds of apples that were harvested each day. Estimate how many pounds of apples were harvested altogether by rounding. Show how you estimated. Answer: The total apples that were harvested altogether are 2163. By rounding the number of pounds the estimated answer is 2160. Explanation: Given The pounds of apples are 514 + 487 + 349 + 421 + 392 = 2163. The estimated answer is 2160. Question 16. In one week, a campground rented 18 cabins at$225 each. About how much did they collect in rent altogether? Show how you estimated.
$4050 Explanation: In one week, a campground rented 18 cabins at$225 each
Find 18 × 225
4050
The rent they collected altogether is $4050. Question 17. The average weight for a guinea pig is 2 pounds. The average weight for a pot belly pig is 45 times greater than the guinea pig. About how much does an average pot belly pig weigh? Show how you estimated. Answer: 90 pounds. Explanation: Given, The average weight for a guinea pig is 2 pounds. The average weight for a pot belly pig is 45 times greater than the guinea pig. So, 2 × 45 = 90 pounds. Hot Problems Question 18. Mathematical PRACTICE 2 Use Number Sense Use the digits 1, 3, 4, and 7 to create two whole numbers whose product is estimated to be about 600. Answer: 34 and 17 are two numbers created from the given digits whose product is estimated to be about 600. Explanation: Let us assume 34 and 17 are two whole numbers from the given digits. If we multiply 34 and 17 then the answer is 34 × 17 = 578. If we are rounding up to the nearest hundreds we will get 600. If we are rounding up the whole numbers the estimation of 34 to the nearest ten is 30 and 17 to the nearest ten is 20 Then the product is 30 × 20 = 600 Hence both the ways 34 and 17 are for the estimated product to be 600. Question 19. ? Building on the Essential Question When is the estimation of products a useful tool? Answer: When the numbers we have are either bigger or smaller and when we buy multiple items which have the same price. ### McGraw Hill My Math Grade 5 Chapter 2 Lesson 8 My Homework Answer Key Estimate by rounding or using compatible numbers. Show how you estimated. Question 1. Answer: 96 Explanation: By multiplying both multiplicand 4 and multiplier 24, we get the value 96. Question 2. Answer: 5928 Explanation: By multiplying both multiplicand 76 and multiplier 78, we get the value 5928. Question 3. Answer: 13716 Explanation: By multiplying both multiplicand 508 and multiplier 27, we get the value 13716. Problem Solving Question 4. For a school assembly, students sit in chairs that are arranged in 53 rows. There are 12 chairs in each row. About how many students can be seated? Show how you estimated. Answer: 636 Explanation: The given question is students sit in chairs that are arranged in 53 rows. There are 12 chairs in each row. 53 × 12 = 636 There are 636 students who would be seated Question 5. Klara bought a dozen bags of bird food for$27. Use compatible numbers to find the approximate cost of six dozen bags of bird food. Show how you estimated.
$160 would cost for six dozen bags of bird food. Explanation: Klara bought a dozen bags of bird food for$27
12 dozen = $27 of bird food = 1 bag 24 dozens =$54 of bird food = 2 bags
36 dozens = $81 = 3 bags 48 dozens =$108 = 4 bags
60 dozens = $135 = 5 bags 72 dozens =$162 = 6 bags
Hence \$160 would cost for six dozen bags of bird food.

Question 6.
Mathematical PRACTICE 3 Find the Error Rico is estimating 139 × 18. Find his mistake and correct it.
100 × 10 = 1,000
2800

Explanation:
The given question is Rico is estimating 139 × 18.
We are here to find the mistake in the given question.
Rico has rounded down 139 to 100 and 18 to 10
Hence 140 × 20
2800

Vocabulary Check

Fill in the blank with the correct term or number to complete the sentence.

Question 7.
Compatible numbers are numbers in a problem that are easy to compute ____.
Add, subtract, multiply or divide mentally.

Explanation:
Compatible numbers are numbers in a problem that is easy to compute Add, subtract, multiply or divide mentally.

Test Practice

Question 8.
On a cross-country vacation, Maria filled her 14-gallon gas tank eleven times. Which is the best estimate of how many gallons of gas she put in the tank altogether?
A. 75 gallons
B. 150 gallons
C. 200 gallons
D. 225 gallons