Solve for the Missing Addend in 1.3 + ? = 1.4

To solve the problem, we need to find the unknown number that when added to 1.3 results in 1.4. This is written mathematically as $1.3 + ? = 1.4$.

We'll solve this by following these steps:

• Step 1: Understand the operation needed. We have a simple addition equation, where we are trying to find the unknown addend.
• Step 2: Rearrange the equation to solve for the unknown number. According to properties of numbers, if $1.3 + ? = 1.4$, then the missing number can be found by subtracting 1.3 from 1.4.
• Step 3: Perform the subtraction: $1.4 - 1.3 = 0.1$.

After performing the calculation, we find that the unknown number is $0.1$.

Therefore, the solution to the problem is $0.1$.