1. The problem is to verify the addition of two numbers: 234 and 456. 2. The formula for addition is: $$a + b = c$$ where $a$ and $b$ are the numbers to add, and $c$ is the sum. 3. Substitute the given values: $$234 + 456 = c$$ 4. Perform the addition: $$234 + 456 = 690$$ 5. Therefore, the result shown in the calculator interface is correct. This simple addition confirms that $234 + 456 = 690$.