For example: 100-35, the columns are vertical? 100

- 35

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From the unit, 0-5 is not enough, from 10 is1; The decimal digit is 0, which is not enough for subtraction. It is 1 calculated from the hundredth digit. Centennial retreat 1 means retreat 100, 10 10. Ten people have 10 and one person has 10. The unit is 10-5 equals 5. The decimal number is 10, 1 equals 9, and 9-3 equals 6. Hundreds are 1- 1 equal to 0. Therefore, when marking the abdication point, it is actually to mark the abdication point from the hundred digits first, then mark the ten digits, and then subtract. (But this is the logical relationship of abdication. In fact, it's not as complicated as going back ten times and subtracting once after doing the problem. )

In fact, these ten people are equivalent to a middleman. He "requested" 100 from 100 and divided it into 10, which means 10. He took one 10 and gave a little, and saved nine 10 himself.