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To solve this problem, we will perform the following steps:
Let's break down the calculation process:
Step 1: Write the numbers in a vertical format.
Step 2: Start by adding the ones digits: . Since 10 is a two-digit number, we write 0 in the ones place and carry 1 over to the tens place.
Step 3: Now, add the tens digits, including the carried 1: .
Since there is no further place value beyond tens in this problem, the result of the addition is:
Therefore, the solution to the problem is 80.
80
\( \begin{aligned} &90 \\ +& \\ &~~9\\ &\underline{\phantom{776}} & \\ \end{aligned} \)
When you add digits and get a number 10 or greater, you write the ones digit in that column and carry the tens digit to the next column on the left. It's like exchanging 10 ones for 1 ten!
Aligning by place value ensures you're adding ones to ones and tens to tens. If numbers aren't lined up correctly, you'll get the wrong answer!
Writing the full sum (like 10) in one column creates numbers with too many digits. For example, writing 10 in the ones place would give you 720 instead of the correct answer 80.
It's better to add from right to left (ones, then tens) because carrying affects the column to the left. Adding left to right makes carrying more confusing!
You can check by adding the numbers horizontally: . You can also try adding in a different order: .
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