Skill: Check addition with subtraction

When you add two numbers, the answer is the whole, and the two numbers you added are its parts. You can check the addition by subtracting one part from the whole. The answer should be the other part.

Example:

$$236+148=384$$

Here, $384$ is the whole, and $236$ and $148$ are the parts.

Check by subtracting $236$ from $384$:

$$384-236$$

• Ones: $4$ cannot subtract $6$, so regroup 1 ten as 10 ones. Then $14-6=8$.
• Tens: There are now 7 tens. $7-3=4$.
• Hundreds: $3-2=1$.

So,

$$384-236=148$$

The subtraction gives the other addend, $148$. This shows that the addition is correct.

You can also check the other way:

$$384-148=236$$

Because both subtractions give the other addend, the equation

$$236+148=384$$

is checked.