To make the expression \( m + [?] - 1.1 \) equivalent to \( m - 1.1 \), we can use the Identity Property of Addition, which states that adding zero to any number does not change its value.
Let's set up the equation:
\[ m + [?] - 1.1 = m - 1.1 \]
To isolate the bracketed term, we can rearrange it:
\[ m + [?] = m - 1.1 + 1.1 \]
Simplifying the right side:
\[ m + [?] = m \]
Now, subtract \( m \) from both sides:
\[ [?] = 0 \]
Therefore, the number that makes the expression equivalent is:
0