Place Value Problem: Converting 3 Ones, 2 Tens, 1 Hundred to Standard Form

To solve this problem, we'll use the concept of place value, where each digit in a number has a different value depending on its position.

Given:

• Number of ones: $3$
• Number of tens: $2$
• Number of hundreds: $1$

Step-by-step explanation:

• Step 1: Start with the hundreds place, which contributes $1 \times 100 = 100$.
• Step 2: Next is the tens place, which contributes $2 \times 10 = 20$.
• Step 3: Finally, the ones place contributes $3 \times 1 = 3$.

Adding these contributions together gives us:

$100 + 20 + 3 = 123$

The number we are looking for, according to the given place values, is $\textbf{123}$.

Therefore, the correct choice is:

Choice 1: $123$