Skill: Add multi-digit whole numbers

To add multi-digit whole numbers:

1. Line up the numbers by place value. Ones go under ones, tens under tens, and so on.
2. Add from right to left, starting with the ones.
3. If a sum is $10$ or more, regroup: write the ones digit and carry the tens digit to the next place.

Example:

$$\begin{array}{r} 458{,}763\\ +276{,}589\\ \hline \end{array}$$

Add each place:

• Ones: $3+9=12$. Write $2$ in the ones place and carry $1$ ten.
• Tens: $6+8+1=15$. Write $5$ and carry $1$.
• Hundreds: $7+5+1=13$. Write $3$ and carry $1$.
• Thousands: $8+6+1=15$. Write $5$ and carry $1$.
• Ten-thousands: $5+7+1=13$. Write $3$ and carry $1$.
• Hundred-thousands: $4+2+1=7$.

The completed addition is:

$$\begin{array}{r} 458{,}763\\ +276{,}589\\ \hline 735{,}352 \end{array}$$

So,

$$458{,}763+276{,}589=735{,}352.$$

Check that the answer is reasonable by estimating:

$$459{,}000+277{,}000\approx736{,}000.$$

Since $735{,}352$ is close to $736{,}000$, the answer makes sense.