附加位最高位为0，舍去，[M]补=00. 10101000

(5)溢出判断，阶码双符号位相同，无溢出，

附加位最高位为0，舍去，[M]补=00. 10101000

(5)溢出判断，阶码双符号位相同，无溢出，

-Additional bits highest bit is 0, rounding, [M] up = 00.10101000 (5) overflow judgment, order code bits of the same symbol double, no overflow, additional bits highest bit is 0, rounding, [M] = 00 Complement . 10,101,000 (5) overflow judgment, order code bits of the same symbol double, no overflow