Section C: Practice Problems Make a Ten: Add Within 100

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We learned to add any 2 two-digit numbers within 100 and write equations to represent our methods.

We added tens and tens and ones and ones.

$37 + 26$
$30 + 20 = 50$
$7 + 6 = 13$
$50 + 13 = 63$

We added ones first to make a new ten.

$37 + 26$
$37 + 3 + 3 = 43$
$43 + 20 = 63$

Find the value of $35 + 48$ .
Show your thinking using drawings, numbers, or words.

Find the value of $16 + 55$ .
Show your thinking using drawings, numbers, or words.
Can you find the value in a different way?

Use your favorite method to find the value of $34 + 59$ .
Why do you like the method you chose?

Choose a two-digit number to add to 46 so that you make a new 10.
Add the numbers.
Write equations to show your thinking.

Elena has a way to find the value of $28 + 47$ without making a 10. Here is her work.
$30 - 2 = 28$
$50 - 3 = 47$
$80 - 5 = 75$

Diego and his friends are working on the same addition problem.

Diego’s method

$40 + 20 = 60$
$60 + 15 = 75$

Lin’s method

$48 + 2 + 5 = 55$
$55 + 20 = 75$

Priya’s method

$40 + 27 = 67$
$67 + 3 + 5 = 75$

Clare wrote some expressions.
Each expression makes a ten.
She spilled water on her work.
Find the digit that could be under each water mark.