Decimal Comparison: Find the Missing Symbol Between 0.1 and 0.4

To solve this problem, we need to compare the two decimal numbers $0.1$ and $0.4$.

First, we look at the tenths place of both numbers:

• $0.1$ has a digit of $1$ in the tenths place.
• $0.4$ has a digit of $4$ in the tenths place.

Since $4$ is greater than $1$, it follows that $0.4$ is greater than $0.1$. Therefore, the correct comparison is $0.1 < 0.4$.

In terms of multiple-choice answers provided, the correct comparison sign would be $\lt$, indicating that $0.1$ is less than $0.4$.

Therefore, the solution to the problem is: $\text{0}.1 \lt 0.4$.