All the solutions provided in McGraw Hill My Math Grade 1 Answer Key PDF Chapter 3 Lesson 9 Add Three Numbers will give you a clear idea of the concepts.

Explore and Explain

Explanation:
I used to model the problem
6 pets live in building A
4 pets live in building B
4 pets live in building C
Add 6 + 4 + 4
6 + 4 = 10
10 + 4 = 14
So, The addition number sentence is 6 + 4 + 4 = 14.

Teacher Directions: Use to model. 6 pets live in building A. 4 pets live in building B. 4 pets live in building C. Add the number of pets in two of the buildings. Then add the number of pets in the third. Write the addition number sentence.

See and Show
You can group numbers and add in any order. Look for doubles. Look for numbers that make a ten.

Add the doubles or make a ten. Write that number. Add the other number to find the sum.

Question 1.

Explanation:
(6 + 4) + 3
= 10 + 3
= 13
So, 6 + 4 + 3 = 13.

Question 2.

Explanation:
4 + 4 = 8
8 + 7 = 15
So, 4 + 7 + 4 = 15.

Question 3.

Explanation:
3 + 3 = 6
6 + 4 = 10
So, 3 + 3 + 6 = 10.

Question 4.

Explanation:
4 + 4 = 8
8 + 2 = 10
So, 4 + 2 + 4 = 10.

Question 5.

Explanation:
Make ten and add the other number
4 + 6 = 10
10 + 2 = 12
So, 4 + 6 + 2 = 12.

Talk Math Tell how you would add the numbers 1 + 2 + 1.
I will first add the doubles and then add the other number
1 + 1 = 2
2 + 2 = 4
So, 1 + 2 + 1 = 4.

On My Own

Add the doubles or make a ten. Write that number. Add the other number to find the sum.

Question 6.

Explanation:
2 + 2 = 4
4 + 3 = 7
SO, 2 + 2 + 3 = 7.

Question 7.

Explanation:
Make ten and then add the other number
7 + 3 = 10
10 + 4 = 14
So, 4 + 7 + 3 = 14.

Question 8.

Explanation:
Make ten an then add the other number
9 + 1 = 10
3 + 10 = 13
So, 3 + 9 + 1 = 13.

Question 9.

Explanation:
4 + 4 = 8
8 + 2 = 10
So, 4 + 4 + 2 = 10.

Question 10.

Explanation:
Make ten and then add the other number
2 + 8 = 10
10 + 1 = 11
So, 2 + 8 + 1 = 11.

Question 11.

Explanation:
3 + 3 = 6
4 + 6 = 10
So, 4 + 3 + 3 = 10.

Question 12.

Explanation:
1 + 1 = 2
2 + 8 = 10
So, 1 + 1 + 8 = 10.

Question 13.

Explanation:
Make ten and then add the other number
6 + 4 = 10
10 + 2 = 12
So, 6 + 4 + 2 = 12.

Problem Solving

Write an addition number sentence to solve.

Question 14.
On Monday, 8 ducks were in the pond. On Tuesday, 4 ducks were in the pond. On Wednesday, 4 ducks were in the pond. How many ducks were in the pond in all?

____ + ____ + ____ = ____ ducks
8 + 4 + 4 = 16 ducks

Explanation:
On Monday, 8 ducks were in the pond
On Tuesday, 4 ducks were in the pond
On Wednesday, 4 ducks were in the pond
4 + 4 = 8
8 + 8 = 16
So, 48 + 4 + 4 = 16
Therefore, 16 ducks were in the pond in all.

Question 15.
An apartment building has 3 doors on the first floor, 5 doors on the second floor, and 5 doors on the third floor. How many doors in all?
___ + ____ + ___ = ___ doors
3 + 5 + 5 = 13 doors

Explanation:
An apartment building has 3 doors on the first floor
5 doors on the second floor
5 doors on the third floor
5 + 5 = 10
3 + 10 = 13
So, 3 + 5 + 5 = 13
Therefore, there are 13 doors in all.

Write Math Hayden says that 8 + 2 + 3 = 15. Tell why Hayden is wrong. Make it right.
__________________________
__________________________
__________________________
__________________________
Hayden is wrong because 8 + 2 + 3 = 13
Make ten and then add the other number
8 + 2 = 10
10 + 3 = 13
So, 8 + 2 + 3 = 13.

McGraw Hill My Math Grade 1 Chapter 3 Lesson 9 My Homework Answer Key

Practice

Add the doubles or make a fen. Write that number. Add the other number to find the sum.

Question 1.

Explanation:
5 + 5 = 10
10 + 2 = 12
So, 5 + 5 + 2 = 12.

Question 2.

Explanation:
Make ten and then add the other number
7 + 3 = 10
10 + 4 = 14
So, 7 + 4 + 3 = 14.

Question 3.

Explanation:
2 + 2 = 4
4 + 9 = 13
So, 2 + 9 + 2 = 13.

Question 4.

Explanation:
Make ten and then add the other number
3 + 7 = 10
10 + 4 = 14
So, 3 + 7 + 4 = 14.

Write an addition number sentence to solve.

Question 5.
Bella sees 4 blue cars, 3 red cars, and 4 black cars. How many cars does she see in all?
___ + ____ + ____ = ____ cars
4 + 3 + 4 = 11 cars

Explanation:
Bella sees 4 blue cars, 3 red cars, and 4 black cars
4 + 3 + 3 =
3 + 3 = 6
4 + 6 = 10
So, 4 + 3 + 3 = 11
Therefore, Bella saw 11 cars in all.

Question 6.
Tom ate 1 slice of pizza. He also ate 9 carrots and 3 strawberries. How many pieces of food did he eat in all?

____ + ____ + ____ = ____ pieces
1 + 9 + 3 = 13 pieces

Explanation:
1 + 9 + 3 =
Make ten and then add the other number
1 + 9 = 10
10 + 3 = 13
So, 1 + 9 + 3 = 13
Therefore, Tom ate 13 pieces of food in all.

Question 7.
Shannon buys 3 white shirts, 3 black shirts, and 4 green shirts. How many shirts does she buy in all?
____ + ____ + ____ = ____ shirts
3 + 3 + 4 = 10 shirts

Explanation:
3 + 3 + 4 =
3 + 3 = 6
6 + 4 = 10
So, 3 + 3 + 4 = 10
Therefore, Shannon buys 10 shirts n all.

Test Practice

Question 8.
2 + 8 + 4 = ____
(A) 10
(B) 11
(C) 12
(D) 14
(D) 14

Explanation:
2 + 8 + 4 =
Make ten and then add the other number
2 + 8 = 10
10 + 4 = 14
So, 2 + 8 + 4 = 14.

Math at Home Place 3 crayons, 3 pencils, and 7 markers in front of your child. Have him or her identify how many there are of each and add the three numbers together to find how many there are in all. Have your child explain their work.

Fluency Practice

Question 1.
4 + 4 = ____
8

Explanation:
The doubles fact is 4 + 4 = 8.

Question 2.
2 + 1 = ____
3

Explanation:
2 + 1 = 3
The sum of 2 and 1 is 3.

Question 3.
1 + 1 = ___
2

Explanation:
The doubles fact is 1 + 1 = 2.

Question 4.
1 + 8 = ____
9

Explanation:
1 + 8 = 9
The sum of 1 and 8 is 9.

Question 5.
1 + 0 = ____
1

Explanation:
1 + 0 = 1
The sum of 1 and 0 is 1.

Question 6.
4 + 2 = ___
6

Explanation:
4 + 2 = 6
The sum of 4 and 2 is 6.

Question 7.
6 + 3 = ___
9

Explanation:
6 + 3 = 9
The sum of 6 and 3 is 9.

Question 8.
2 + 7 = ___
9

Explanation:
2 + 7 = 9
The sum of 2 and 7 is 9.

Question 9.
3 + 2 = ____
5

Explanation:
3 + 2 = 5
The sum of 3 and 2 is 5.

Question 10.
2 + 5 = ____
7

Explanation:
2 + 5 = 7
The sum of 2 and 5 is 7.

Question 11.
6 + 1 = ____
7

Explanation:
6 + 1 = 7
The sum of 6 and 1 is 7.

Question 12.
5 + 4 = ___
9

Explanation:
5 + 4 = 9
The sum of 5 and 4 s 9.

Question 13.

Explanation:
The sum of 7 and 3 is 10.

Question 14.

Explanation:
The sum of 3 and 3 is 6
It is a doubles fact.

Question 15.

Explanation:
The sum of 2 and 2 is 4
It is a doubles fact.

Question 16.

Explanation:
The sum of 6 and 4 is 10
6 + 4 = 10.

Question 17.

Explanation:
The sum of 0 and 9 is 9
0 + 9 = 9.

Question 18.

Explanation:
The sum of 0 and 5 is 5
0 + 5 = 5.

Question 19.

Explanation:
The sum of 7 and 1 is 8
7 + 1 = 8.

Question 20.

Explanation:
The sum of 1 and 3 is 4
1 + 3 = 4.

Question 21.

Explanation:
The sum of 0 and 0 is 0.

Fluency Practice

Question 1.
0 + 8 = ____
8

Explanation:
0 + 8 = 8
The sum of 0 and 8 is 8.

Question 2.
3 + 5 = ____
8

Explanation:
3 + 5 = 8
The sum of 3 and 5 is 8.

Question 3.
7 + 9 = ____
16

Explanation:
The sum of 7 and 9 is 16.
7 + 9 = 16

Question 4.
6 + 6 = ___
12

Explanation:
The sum of 6 and 6 is 12
6 + 6 = 12 is a doubles fact.

Question 5.
1 + 6 = ____
7

Explanation:
1 + 6 = 7
The sum of 1 and 6 is 7.

Question 6.
4 + 3 = ___
7

Explanation:
4 + 3 = 7
The sum of 4 and 3 is 7.

Question 7.
6 + 7 = ____
13

Explanation:
6 + 7 = 13
The sum of 6 and 7 is 13.

Question 8.
7 + 7 = ____
14

Explanation:
The sum of 7 and 7 is 14
7 + 7 = 14 is a doubles fact.

Question 9.
3 + 8 = ___
11

Explanation:
3 + 8 = 11
The sum of 3 and 8 is 11.

Question 10.
2 + 3 = ____
5

Explanation:
2 + 3 = 5
The sum of 2 and 3 is 5.

Question 11.
9 + 0 = ___
9

Explanation:
9+ 0 = 9
The sum of 9 and 0 is 9.

Question 12.
8 + 1 = ____
9

Explanation:
8 + 1 = 9
The sum of 8 and 1 is 9.

Question 13.

Explanation:
The sum of 4 and 7 is 11.

Question 14.

Explanation:
The sum of 8 and 4 is 12.

Question 15.

Explanation:
The sum of 10 and 2 is 12.

Question 16.

Explanation:
The sum of 5 and 2 is 7.

Question 17.

Explanation:
The sum of 9 and 6 is 15.

Question 18.

Explanation:
The sum of 5 and 6 is 11.

Question 19.

Explanation:
The sum of 10 and 10 is 20
It is a doubles fact.

Question 20.