Solve, using properties/ methods that simplify the calculations:
`345+999`

Options

A. `1343`
B. `1344`
C. `1345`
D. `1346`

Answer

To solve the problem of adding 345 and 999 using properties that simplify calculations, we can break down the numbers into simpler parts. Here’s a step-by-step solution:

### Step 1: Break down the numbers
We can express 345 and 999 in a way that makes the addition easier.
- We can write 345 as \(300 + 45\).
- We can write 999 as \(1000 - 1\).

### Step 2: Rewrite the addition
Now, we can rewrite the addition as:
\[ 345 + 999 = (300 + 45) + (1000 - 1) \]

### Step 3: Group the terms
Next, we can group the terms together:
\[ = 300 + 45 + 1000 - 1 \]

### Step 4: Add the whole numbers
Now, we can add the whole numbers together:
\[ 300 + 1000 = 1300 \]

### Step 5: Add the remaining parts
Now, we add the remaining parts:
\[ 1300 + 45 = 1345 \]

### Step 6: Subtract 1
Finally, we subtract 1 from the total:
\[ 1345 - 1 = 1344 \]

### Final Answer
Thus, the sum of 345 and 999 is:
\[ \boxed{1344} \]