Transcript Name ______ Estimating Products Gr. 6__ And Quotients

Name ____ Gr. 6__ Lesson 2 Estimating Dec.2
Products And Quotients
Objective: to estimate products and quotients with decimals.
Name ______ Estimating Products
And Quotients
Gr. 6__
Read the top of page 92 about how much string Bernie
needs.
Name ______ Estimating Products
And Quotients
Gr. 6__
Read the top of page 92 about how much string Bernie
needs.
What does the word “about” mean?
Name ______ Estimating Products
And Quotients
Gr. 6__
Read the top of page 92 about how much string Bernie
needs.
What does the word “about” mean?
“About” means “only an estimate is needed”.
Name ______ Estimating Products
And Quotients
Gr. 6__
Read the top of page 92 about how much string Bernie
needs.
What does the word “about” mean?
“About” means “only an estimate is needed”.
How can you use “decimal benchmarks” to help you
estimate?
Name ______ Estimating Products
And Quotients
Gr. 6__
Read the top of page 92 about how much string Bernie
needs.
What does the word “about” mean?
“About” means “only an estimate is needed”.
How can you use “decimal benchmarks” to help you
estimate?
Well... 1.15 is closer to 1 than 2, I will multiply ≈
Name ______ Estimating Products
And Quotients
Gr. 6__
Read the top of page 92 about how much string Bernie
needs.
What does the word “about” mean?
“About” means “only an estimate is needed”.
How can you use “decimal benchmarks” to help you
estimate?
Well... 1.15 is closer to 1 than 2, I will multiply ≈ 1m X 6 ≈ 6m
Bernie will need about 6 metres of string altogether.
Name ______ Estimating Products
And Quotients
Gr. 6__
Read the top of page 92 about how much string Bernie
needs.
What does the word “about” mean?
“About” means “only an estimate is needed”.
How can you use “decimal benchmarks” to help you
estimate?
Well... 1.15 is closer to 1 than 2, I will multiply ≈ 1m X 6 ≈ 6m
Bernie will need about 6 metres of string altogether.
OR better yet, “Bernie will need a little more than 6m of
string.”
Name ______ Estimating Products
And Quotients
Gr. 6__
Page 92
EXPLORE : Estimate your 2 answers, recording HOW you
estimated.
Name ______ Estimating Products
And Quotients
CONNECT: 3 strategies to estimate:
1) Front-end Estimation:
2) Decimal Benchmarks:
3) Compatible Numbers:
Gr. 6__
Name ______ Estimating Products
And Quotients
Gr. 6__
CONNECT: 3 strategies to estimate:
1) Front-end Estimation: simply chop off all digits and only
use the place value of the front digit.
2) Decimal Benchmarks:
3) Compatible Numbers:
Name ______ Estimating Products
And Quotients
Gr. 6__
CONNECT: 3 strategies to estimate:
1) Front-end Estimation: simply chop off all digits and only
use the place value of the front digit.
Ex: 2.73 X 8 ≈
2) Decimal Benchmarks:
3) Compatible Numbers:
Name ______ Estimating Products
And Quotients
Gr. 6__
CONNECT: 3 strategies to estimate:
1) Front-end Estimation: simply chop off all digits and only
use the place value of the front digit.
Ex: 2.73 X 8 ≈ 2 X 8 ≈ 16 NOT Good! Underestimated! L
2) Decimal Benchmarks:
3) Compatible Numbers:
Name ______ Estimating Products
And Quotients
Gr. 6__
CONNECT: 3 strategies to estimate:
1) Front-end Estimation: simply chop off all digits and only
use the place value of the front digit.
Ex: 2.73 X 8 ≈ 2 X 8 ≈ 16 NOT Good! Underestimated! L
2) Decimal Benchmarks: Find which number the decimal is
closer to...
3) Compatible Numbers:
Name ______ Estimating Products
And Quotients
Gr. 6__
CONNECT: 3 strategies to estimate:
1) Front-end Estimation: simply chop off all digits and only
use the place value of the front digit.
Ex: 2.73 X 8 ≈ 2 X 8 ≈ 16 NOT Good! Underestimated! L
2) Decimal Benchmarks: Find which number the decimal is
closer to...
Ex: 2.73 X 8 ≈
Name ______ Estimating Products
And Quotients
Gr. 6__
CONNECT: 3 strategies to estimate:
1) Front-end Estimation: simply chop off all digits and only
use the place value of the front digit.
Ex: 2.73 X 8 ≈ 2 X 8 ≈ 16 NOT Good! Underestimated! L
2) Decimal Benchmarks: Find which number the decimal is
closer to...
Ex: 2.73 X 8 ≈ 3 X 8 ≈ 24 Better! Overestimated, but closer J
3) Compatible Numbers:
Name ______ Estimating Products
And Quotients
Gr. 6__
CONNECT: 3 strategies to estimate:
1) Front-end Estimation: simply chop off all digits and only
use the place value of the front digit.
Ex: 2.73 X 8 ≈ 2 X 8 ≈ 16 NOT Good! Underestimated! L
2) Decimal Benchmarks: Find which number the decimal is
closer to...
Ex: 2.73 X 8 ≈ 3 X 8 ≈ 24 Better! Overestimated, but closer J
3) Compatible Numbers: Use numbers that are easy to use
mentally.
Name ______ Estimating Products
And Quotients
Gr. 6__
CONNECT: 3 strategies to estimate:
1) Front-end Estimation: simply chop off all digits and only
use the place value of the front digit.
Ex: 2.73 X 8 ≈ 2 X 8 ≈ 16 NOT Good! Underestimated! L
2) Decimal Benchmarks: Find which number the decimal is
closer to...
Ex: 2.73 X 8 ≈ 3 X 8 ≈ 24 Better! Overestimated, but closer J
3) Compatible Numbers: Use numbers that are easy to use
mentally.
Ex: 575.94 / 4 ≈
Name ______ Estimating Products
And Quotients
Gr. 6__
CONNECT: 3 strategies to estimate:
1) Front-end Estimation: simply chop off all digits and only
use the place value of the front digit.
Ex: 2.73 X 8 ≈ 2 X 8 ≈ 16 NOT Good! Underestimated! L
2) Decimal Benchmarks: Find which number the decimal is
closer to...
Ex: 2.73 X 8 ≈ 3 X 8 ≈ 24 Better! Overestimated, but closer J
3) Compatible Numbers: Use numbers that are easy to use
mentally.
Ex: 575.94 / 4 ≈ 600 /4 because 60 is a multiple of 4 ≈ 150
Name ______ Estimating Products
And Quotients
Gr. 6__
CONNECT: 3 strategies to estimate:
1) Front-end Estimation: simply chop off all digits and only
use the place value of the front digit.
Ex: 2.73 X 8 ≈ 2 X 8 ≈ 16 NOT Good! Underestimated! L
2) Decimal Benchmarks: Find which number the decimal is
closer to...
Ex: 2.73 X 8 ≈ 3 X 8 ≈ 24 Better! Overestimated, but closer J
3) Compatible Numbers: Use numbers that are easy to use
mentally.
Ex: 575.94 / 4 ≈ 600 /4 because 60 is a multiple of 4 ≈ 150
OR 560/4 because 56 is a multiple of 4 ≈ 140
Name ______ Estimating Products
And Quotients
Gr. 6__
CONNECT: Let’s add a 4th strategy to estimate if you need to
round off 2 decimals:
4) Over/Under Estimation:
Name ______ Estimating Products
And Quotients
Gr. 6__
CONNECT: Let’s add a 4th strategy to estimate if you need to
round off 2 decimals:
4) Over/Under Estimation: Round one of the decimals up
and to balance that over-estimate, round the other decimal
off.
Ex #1: 2.87 X 9.14 ≈
Name ______ Estimating Products
And Quotients
Gr. 6__
CONNECT: Let’s add a 4th strategy to estimate if you need to
round off 2 decimals:
4) Over/Under Estimation: Round one of the decimals up
and to balance that over-estimate, round the other decimal
off.
Ex #1: 2.87 X 9.14 ≈ 3 X 9 ≈ 27
Name ______ Estimating Products
And Quotients
Gr. 6__
CONNECT: Let’s add a 4th strategy to estimate if you need to
round off 2 decimals:
4) Over/Under Estimation: Round one of the decimals up
and to balance that over-estimate, round the other decimal
off.
Ex #1: 2.87 X 9.14 ≈ 3 X 9 ≈ 27
Ex. #2: 19.389 + 61.704 ≈
Name ______ Estimating Products
And Quotients
Gr. 6__
CONNECT: Let’s add a 4th strategy to estimate if you need to
round off 2 decimals:
4) Over/Under Estimation: Round one of the decimals up
and to balance that over-estimate, round the other decimal
off.
Ex #1: 2.87 X 9.14 ≈ 3 X 9 ≈ 27
Ex. #2: 19.389 + 61.704 ≈ 20 + 60 ≈ 80
Name ______ Estimating Products
And Quotients
PRACTICE on Page 94:
#1, #2, #3, #4
Gr. 6__
Name ______ Estimating Products
And Quotients
Gr. 6__
P.94:
1. Estimate each product or quotient. Which strategies did you use?
Tell if your estimate is an overestimate or an underestimate.
a) 7.01 X 9 b) 3.8 X 7
c) 11.85 X 5 d) 19.925 X 4
e) 9.8  5
f) 12.31  2
g) 56.093  7 h) 225.3  5
Name ______ Estimating Products
And Quotients
Gr. 6__
P.94:
1. Estimate each product or quotient. Which strategies did you use?
Tell if your estimate is an overestimate or an underestimate.
a) 7.01 X 9 b) 3.8 X 7
c) 11.85 X 5 d) 19.925 X 4
≈ 7 X 9 ≈ 63
Under
e) 9.8  5
f) 12.31  2 g) 56.093  7 h) 225.3  5
Name ______ Estimating Products
And Quotients
Gr. 6__
P.94:
1. Estimate each product or quotient. Which strategies did you use?
Tell if your estimate is an overestimate or an underestimate.
a) 7.01 X 9 b) 3.8 X 7
c) 11.85 X 5 d) 19.925 X 4
≈ 7 X 9 ≈ 63
≈ 4 X 7 ≈ 28
Under
Over
e) 9.8  5
f) 12.31  2 g) 56.093  7 h) 225.3  5
Name ______ Estimating Products
And Quotients
Gr. 6__
P.94:
1. Estimate each product or quotient. Which strategies did you use?
Tell if your estimate is an overestimate or an underestimate.
a) 7.01 X 9 b) 3.8 X 7
c) 11.85 X 5 d) 19.925 X 4
≈ 7 X 9 ≈ 63
≈ 4 X 7 ≈ 28 ≈ 12 X 5 ≈ 60
Under
Over
Over
e) 9.8  5
f) 12.31  2 g) 56.093  7 h) 225.3  5
Name ______ Estimating Products
And Quotients
Gr. 6__
P.94:
1. Estimate each product or quotient. Which strategies did you use?
Tell if your estimate is an overestimate or an underestimate.
a) 7.01 X 9 b) 3.8 X 7
c) 11.85 X 5 d) 19.925 X 4
≈ 7 X 9 ≈ 63
≈ 4 X 7 ≈ 28 ≈ 12 X 5 ≈ 60 ≈ 20 X 4 ≈ 80
Under
Over
Over
Over
e) 9.8  5
f) 12.31  2 g) 56.093  7 h) 225.3  5
Name ______ Estimating Products
And Quotients
Gr. 6__
P.94:
1. Estimate each product or quotient. Which strategies did you use?
Tell if your estimate is an overestimate or an underestimate.
a) 7.01 X 9 b) 3.8 X 7
c) 11.85 X 5 d) 19.925 X 4
≈ 7 X 9 ≈ 63
≈ 4 X 7 ≈ 28 ≈ 12 X 5 ≈ 60 ≈ 20 X 4 ≈ 80
Under
Over
Over
Over
e) 9.8  5
f) 12.31  2 g) 56.093  7 h) 225.3  5
≈ 10 / 5 ≈ 2
Over
Name ______ Estimating Products
And Quotients
Gr. 6__
P.94:
1. Estimate each product or quotient. Which strategies did you use?
Tell if your estimate is an overestimate or an underestimate.
a) 7.01 X 9 b) 3.8 X 7
c) 11.85 X 5 d) 19.925 X 4
≈ 7 X 9 ≈ 63
≈ 4 X 7 ≈ 28 ≈ 12 X 5 ≈ 60 ≈ 20 X 4 ≈ 80
Under
Over
Over
Over
e) 9.8  5
f) 12.31  2 g) 56.093  7 h) 225.3  5
≈ 10 / 5 ≈ 2 ≈ 12 / 2 ≈ 6
Over
Under
Name ______ Estimating Products
And Quotients
Gr. 6__
P.94:
1. Estimate each product or quotient. Which strategies did you use?
Tell if your estimate is an overestimate or an underestimate.
a) 7.01 X 9 b) 3.8 X 7
c) 11.85 X 5 d) 19.925 X 4
≈ 7 X 9 ≈ 63
≈ 4 X 7 ≈ 28 ≈ 12 X 5 ≈ 60 ≈ 20 X 4 ≈ 80
Under
Over
Over
Over
e) 9.8  5
f) 12.31  2 g) 56.093  7 h) 225.3  5
≈ 10 / 5 ≈ 2 ≈ 12 / 2 ≈ 6 ≈ 56 / 7 ≈ 8
Over
Under
Over
Name ______ Estimating Products
And Quotients
Gr. 6__
P.94:
1. Estimate each product or quotient. Which strategies did you use?
Tell if your estimate is an overestimate or an underestimate.
a) 7.01 X 9 b) 3.8 X 7
c) 11.85 X 5 d) 19.925 X 4
≈ 7 X 9 ≈ 63
≈ 4 X 7 ≈ 28 ≈ 12 X 5 ≈ 60 ≈ 20 X 4 ≈ 80
Under
Over
Over
Over
e) 9.8  5
f) 12.31  2 g) 56.093  7 h) 225.3  5
≈ 10 / 5 ≈ 2 ≈ 12 / 2 ≈ 6 ≈ 56 / 7 ≈ 8 ≈ 200 / 5 ≈ 40
Over
Under
Over
Under
Name ______ Estimating Products
And Quotients
Gr. 6__
P.94:
2. Waldo paid $29.85 for 3 admission tickets to the Calgary Tower.
Estimate the cost of one admission ticket.
Name ______ Estimating Products
And Quotients
Gr. 6__
P.94:
2. Waldo paid $29.85 for 3 admission tickets to the Calgary Tower.
Estimate the cost of one admission ticket.
$29.85 / 3
≈ $30 / 3 ≈ $10
One admission ticket to the Calgary Tower is
about $10.
Name ______ Estimating Products
And Quotients
Gr. 6__
P.94:
3. A pair of ice cleats for ice fishing costs $14.89. About how much will
6 pairs of ice cleats cost? How did you find out?
Name ______ Estimating Products
And Quotients
Gr. 6__
P.94:
3. A pair of ice cleats for ice fishing costs $14.89. About how much will
6 pairs of ice cleats cost? How did you find out?
$14.89 X 6
≈ $15 X 6 ≈ $90
6 pairs of ice cleats cost about $90. I rounded up to $15 and x by 6.
Name ______ Estimating Products
And Quotients
Gr. 6__
P.94:
4. Estimate the perimeter of each square. Tell if your estimate is an
overestimate or an underestimate. How do you know?
a)
b)
c)
1.3cm
2.1cm
2.6cm
Name ______ Estimating Products
And Quotients
Gr. 6__
P.94:
4. Estimate the perimeter of each square. Tell if your estimate is an
overestimate or an underestimate. How do you know?
a)
b)
c)
1.3cm
A = 4s or 4 X side
= 4 X 1.3
≈ 4 X 1 ≈ 4cm
Under
2.1cm
2.6cm
Name ______ Estimating Products
And Quotients
Gr. 6__
P.94:
4. Estimate the perimeter of each square. Tell if your estimate is an
overestimate or an underestimate. How do you know?
a)
b)
c)
1.3cm
A = 4s or 4 X side
= 4 X 1.3
≈ 4 X 1 ≈ 4cm
Under
2.1cm
A = 4s or 4 X side
= 4 X 2.1
≈ 4 X 2 ≈ 8cm
Under
2.6cm
Name ______ Estimating Products
And Quotients
Gr. 6__
P.94:
4. Estimate the perimeter of each square. Tell if your estimate is an
overestimate or an underestimate. How do you know?
a)
b)
c)
1.3cm
A = 4s or 4 X side
= 4 X 1.3
≈ 4 X 1 ≈ 4cm
Under
2.1cm
A = 4s or 4 X side
= 4 X 2.1
≈ 4 X 2 ≈ 8cm
Under
2.6cm
A = 4s or 4 X side
= 4 X 2.6
≈ 4 X 3 ≈ 12cm
Over