A、擬舍棄數(shù)字的最左一位數(shù)字小于5，則進一，保留其余各位數(shù)字不變
B、擬舍棄數(shù)字的最左一位數(shù)字大于5，則舍去，即保留數(shù)字的末尾數(shù)字加1
C、擬舍棄數(shù)字的最左一位數(shù)字是5，且其后有非0數(shù)字時進一，即保留數(shù)字的末尾數(shù)字不變
D、擬舍棄數(shù)字的最左一位數(shù)字是5，且其后無數(shù)字或皆為0時，若所保留的末位數(shù)字為奇數(shù)則進一，即保留數(shù)字的末尾數(shù)字加1；若所保留的末位數(shù)字為偶數(shù)，則舍去