5. In a single-precision IEEE-754 floating-point format, when the number is +underflow, the biased exponent (in decimal) is ___

6. In a single-precision IEEE-754 floating-point format, when the number is +underflow, the true exponent (in decimal) is ___

7. In a single-precision IEEE-754 floating-point format, when the number is +infinity, the sign bit of the number is ___