What did the zero say to the eight?

In this lesson you will solve addition problems by using

complements of ten and their multiples.

What did the zero say to the eight?

Nice belt!

No, no not that kind of

compliment.complements

Ron & Hermione

Oreo Cookie & Oreo Cream

Park Place & Boardwalk

Let’s Review

1 + 9

2 + 8

3 + 7

4 + 6

5 + 5

40 + 60 = 100

A Common Mistake

A common mistake is to mix up the place value of complements.

4 + 6 14 + 6

14 + 60

Core Lesson

3 + 7 = 10

300 + 700 = 1000 3 H + 7 H = 10 H

1000 – 800 = 200 10 H – 8 H = 2 H

Core Lesson

2,360 + 1,440

6 T + 4 T = 10 T

3,000 700 100+ + =3,800

Core Lesson

623 + 293 = ? 

6 H + 2 T + 3 O

9 T + 3 O

2 H +

8 T + 13 O

800 100 16+ + = 916

In this lesson you have learned how to solve addition problems by using complements of ten

and their multiples.

Guided Practice

1,158 + 4, 31 = 6,089

What number goes in the blank?

1 , 1 5 8

+ 4 , 3 1

6 , 0 8 9

1

9

Extension Activities

Play a game with the class in which students face forward and you say one half of a complement such as “6” the students then turn backwards and say the other half, “4”. You can make this more challenging by saying “700” and students say “300” or “650” and “350”.

Extension Activities

For students who need more help adding complements keep base ten blocks on hand, and have students rewrite equations with larger numbers in terms of one’s and “hundreds” written out in words or as a letter, so they can see the complements more readily.

Quick Quiz

Add 1,732 + 2,365 using what you know about complements.

Decompose 3,467 to add it to 5,722 using complements.