Solve Three-Digit Addition: 137 + 523 in Vertical Format

To solve this problem, we will perform vertical addition of the numbers 137 and 523:

• Step 1: Add the ones place: $7 + 3 = 10$. We write down 0 and carry over the 1 to the tens place.
• Step 2: Add the tens place: $3 + 2 = 5$, and include the carried over 1, totaling $5 + 1 = 6$. We write down 6.
• Step 3: Add the hundreds place: $1 + 5 = 6$. We write down 6.

By following these steps, the sum of the numbers 137 and 523 is calculated as 660.

Therefore, the solution to the problem is indeed $660$, which matches with choice 2 among the given options.