Analysis: 9 in the minuend is regarded as 6, that is, the minuend is less than 9-6=3, and the difference is less than 3; The fifth error of the tenth decimal place is regarded as 2, that is, 50-20=30 MINUS, and the difference is more than 30; So the calculated difference is 30-3=27, and the correct number should be 303+3-30.

Answer: Minus 9-6=3.

The reduction is 50-20=30.

The difference is 30-3=27.

Correct difference: 303-27=276

The correct number is 276.

Comments: According to the variation of meiosis and meiosis, we can get the variation of business trip, and then get the correct difference.

Extended data:

In addition and subtraction, sum and addend, difference and minuend, and the changes of minuend all have certain laws.

1, in addition, addend increases or decreases, and also increases or decreases.

2. In subtraction, if the minuend increases or decreases, the difference will also increase or decrease; When the reduction increases or decreases, the difference decreases or increases.

3. In the subtraction formula, the minuend+subtraction+difference = minuend+minuend = minuend × 2.

In other words, the sum of the minuend, subtraction and difference is twice that of the minuend.