When you subtract two numbers, you subtract a subtrahend from a minuend . 当你作两个数的减法时，你用一个被减数去减另一个减数。
2.
When the final borrow is 1, the minuend is reentered into the divided storage register . 当最后借位为1时，将被减数重新存入被除数存贮寄存器。
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Look at the minuend and subtrahend . they both add or subtract the same number . the differences are the same 小结：被减数减少(或增加) ，减数也作相应的减少(或增加) ，差不变。
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An arithmetically negative carry . it occurs in performing subtraction when the subtrahend is larger than the minuend in a particular digit position 一种算术负进位,它出现在某一特定的数位上减数大于被减数的减法运算中。
