Adding Three or More Multi-Digit Numbers

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How do you add three numbers like $123 + 45 + 6$?

Stack all three numbers vertically, making sure to line up the ones, tens, and hundreds columns carefully before you start adding.

$$123 + 45 + 6 = ?$$

$$\begin{array}{rr} & 123 \\ + & 45 \\ + & 6 \\ \hline & 174 \end{array}$$Ones: $3+5+6=14$. Write $4$, carry $1$. Tens: $1+2+4=7$. Hundreds: Bring down the $1$.

When adding a column, if the sum is $25$, what do you do?

Write the $5$ below the column and carry the $2$ to the top of the next column to the left.

$$48 + 36 + 29 = ?$$

$$\begin{array}{rr} & 48 \\ + & 36 \\ + & 29 \\ \hline & 113 \end{array}$$Ones: $8+6+9=23$. Write $3$, carry $2$. 2. Tens: $2+4+3+2=11$. Write $11$.

What number would you carry from the ones column in $19 + 29 + 39$?

The sum of the ones is $9+9+9=27$. You would write the $7$ and carry the $2$.

$$115 + 216 + 317 = ?$$

$$\begin{array}{rr} & 115 \\ + & 216 \\ + & 317 \\ \hline & 648 \end{array}$$Ones: $5+6+7=18$. Write $8$, carry $1$. Tens: $1+1+1+1=4$. Hundreds: $1+2+3=6$.

$$50 + 60 + 70 = ?$$

$$\begin{array}{rr} & 50 \\ + & 60 \\ + & 70 \\ \hline & 180 \end{array}$$Ones: $0+0+0=0$. 2. Tens: $5+6+7=18$. Write $8$ in the tens place and carry the $1$ to the hundreds place.

Is it possible to carry a number bigger than $1$?

Yes. If a column adds up to $23$, you carry a $2$. If it adds up to $34$, you carry a $3$. This often happens when adding three or more numbers.

$$251 + 142 + 333 = ?$$

$$\begin{array}{rr} & 251 \\ + & 142 \\ + & 333 \\ \hline & 726 \end{array}$$

$$109 + 208 + 307 + 406 = ?$$

$$1030$$ Ones: $9+8+7+6=30$. Write $0$, carry $3$. Tens: $3+0+0+0+0=3$. Hundreds: $1+2+3+4=10$. Write $10$.

$$25 + 25 + 25 + 25 = ?$$

$$100$$