Solve the Decimal Addition: 0.4 + 0.3

To solve the decimal addition $0.4 + 0.3$, we will follow these steps:

• Step 1: Line up the numbers by the decimal point.

• Step 2: Add the decimal fractions directly as both numbers have only one digit after the decimal point.

• Step 3: Sum the values and retain the decimal point in the same position for the result.

Let's begin the calculation:

Write the numbers aligning them by the decimal point:

$0.4$
$+0.3$
_______
$0.7$

Adding the two numbers $0.4$ and $0.3$ gives $0.7$.

Therefore, the solution to the problem is $0.7$, which matches choice 1.