Decimal number with exponent notation are not allowed.

十进制的说明符号不被认可。

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An exponent is a mathematical notation indicating the power to which a number is to be raised.

指数是一个数学符号，表明数字增倍的量。

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Floating-Point literals may also be represented using exponential notation: a real number followed by the letter e(or E), followed by an optional plus or minus sign, followed by an integer exponent.

此外，还可以使用指数记数法表示浮点型直接量，即实数后跟随字母e或E，后面加上正负号，其后再加一个整型指数。

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