403-654:3+398*2

To solve this expression, you need to follow the order of operations, which is parentheses, exponents, multiplication and division (from left to right), and addition and subtraction (from left to right).

Let's break down the expression step by step:

1. Calculate the multiplication: 398 * 2 = 796.

2. Rewrite the expression with the result: 403 - 654:3 + 796.

3. Calculate the division: 654 divided by 3 = 218.

4. Rewrite the expression with the result: 403 - 218 + 796.

5. Calculate the addition and subtraction: 403 - 218 + 796 = 981.

Therefore, the answer is 981.