Compare Numbers 10⊡ and 140: Determining the Correct Inequality Sign

To solve this problem, we must determine which inequality sign fits the comparison $10\Box?140$.

• Step 1: Consider the expression $10\Box$ as $100 + \Box$, where $\Box$ is any digit from 0 to 9.
• Step 2: Calculate the range of values for $10\Box$:
  If $\Box = 0$, then $10\Box = 100 + 0 = 100$.
  If $\Box = 9$, then $10\Box = 100 + 9 = 109$.
• Step 3: Compare all possible values of $10\Box$ (100 to 109) with 140.
• Step 4: Since 109, the largest possible value, is less than 140, for any digit $\Box$, $10\Box$ will always be less than 140.

Therefore, the correct inequality is $10\Box < 140$. The proper sign for the expression is $<$.