# Section B: Practice Problems Make a Ten: Add One- and Two-Digit Numbers

## Section Summary

Details

We added one-digit numbers and two-digit numbers.
We used different methods to add.
We learned you can think of counting on to make a new ten.

We also saw you can think of adding all the ones and then the tens.
Sometimes when you add the ones you might be able to make a new ten.

## Problem 1 (Lesson 5)

Find the value of each sum.
Show your thinking using drawings, numbers, or words.

## Problem 2 (Lesson 6)

Find the value of each sum.
Show your thinking using drawings, numbers, or words.

## Problem 3 (Lesson 7)

Find the value of each sum.
Show your thinking using drawings, numbers, or words.

1. How are the problems the same?
How are they different?

## Problem 4 (Exploration)

Choose five numbers from below to make a sum with a value greater than 50 but less than 99.

3

5

6

7

8

10

20

30

40

Use equations or drawing to show your thinking.

## Problem 5 (Exploration)

Here is how Lin found the value of .

“I know . Then I add tens and get .

1. Why does Lin’s method work? Show your thinking using drawings, numbers, or words.

2. Use Lin’s method to find the value of .

## Problem 6 (Exploration)

Noah’s brother spilled water on his math work.
Help Noah figure out what the missing number is.

1. The missing number makes the value of the sum greater than 50, with a 0 in the ones place.

What could the missing number be?

2. The missing number is a two-digit number that makes the value 75.

What could the missing number be?

3. The missing number is a two-digit number that makes a value that is more than 80 but less than 90.

What could the missing number be?

## Problem 7 (Exploration)

Priya is playing the game Target Numbers.
Priya starts at 25 and picks these six cards:

1

2

3

5

6

8

She chooses whether to add that many tens or ones for each card.
What is the highest score she can get without going over 95?
Use equations to show your thinking.