Formula: plus 9 minus 1, plus 8 minus 2, plus 7 minus 3, plus 6 minus 4, plus 5 minus 6, plus 3 minus 7, plus 2 minus 8, plus/kloc-0 minus 9. (Note: The words added in the oral decision refer to the number in the unit. )

For example: 26+38=64? Solution? If you add 8, you subtract 2. Who subtracts 2? 26 minus 2 equals 6. Three out of 38 will get four points.

(Note: How to round the last ten digits is 1, I enter 2, 2, 3, 4, and so on. Where are you taking it? It reaches the tenth place in the second two digits. If this is 3, I enter 4, and these two digits are 2+4=6. ) Here, 26+38=64 means that 6-2=4 is written with one digit, and 3 into 4 plus 2 means that 6 is written with ten digits.

2, two-digit subtraction, two-digit abdication subtraction.

Oral decision:? Minus 9 plus 1, 8 plus 2, 7 plus 3, 6 plus 4, 5 plus 5, 4 plus 6, 3 plus 7, 2 plus 8, and 1 plus 9. (Note: orally decided to reduce a few words, that is, reduce one digit).

Example: 73-46=27, solution: subtract 6 and add 4, who will add 4? Three plus four equals seven. Written in one place, the decimal place of subtraction is four. I will retire. Who will retire? 7 returns 5, which is 27.

(Note: How to abdicate? The decimal place of subtraction is 1, you retreat 2, if 2, you retreat 3, if 3, you retreat 4, and so on. However, this retreat can only be carried out if the single digit is not reduced enough. If you reduce it enough, you can directly reduce one digit, and you can directly determine the number by subtracting ten digits from ten digits. )