The problem of the accuracy of floating-point numbers

it is a bit confusing to see that the 23-bit Mantissa determines that the single-precision floating-point decimal precision is 7 digits. The 23-bit binary can only show that the M of the binary Mantissa 1.M can represent 2 ^ 23 digits. How can it be determined that the decimal point can be exactly 7 digits after the decimal point? Please give me some advice!

Mar.06,2021

2 ^ 23 = 8388608-7 bits total

MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b3bb4f-2b800.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b3bb4f-2b800.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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