Solve the following addition problems using the number line concept: 6 + 2, 1 + 4, 2 + 5, 6 + 1, 4 + 3.

To find $6 + 2$, start at 6 on the number line and jump 2 numbers ahead.
$6 \to 7 \to 8$.

$$6 + 2 = 8$$

The sum is $\boxed{\text{8}}$.

To find $1 + 4$, start at 1 on the number line and jump 4 numbers ahead.
$1 \to 2 \to 3 \to 4 \to 5$.

$$1 + 4 = 5$$

The sum is $\boxed{\text{5}}$.

To find $2 + 5$, start at 2 on the number line and jump 5 numbers ahead.
$2 \to 3 \to 4 \to 5 \to 6 \to 7$.

$$2 + 5 = 7$$

The sum is $\boxed{\text{7}}$.

To find $6 + 1$, start at 6 on the number line and jump 1 number ahead.
$6 \to 7$.

$$6 + 1 = 7$$

The sum is $\boxed{\text{7}}$.

To find $4 + 3$, start at 4 on the number line and jump 3 numbers ahead.
$4 \to 5 \to 6 \to 7$.

$$4 + 3 = 7$$

The sum is $\boxed{\text{7}}$.