Proposal for solving fraction_part causing 1.09e-6 generated as 1.9e-6 issue #792 #242

Job	Run time
posix (STD=17 JOB=test/x3, boost, clang-18 libc++-18-dev libc++abi-18-dev libunwind-18-dev jq cc...	4m 55s
posix (STD=17 JOB=test/x3, boost, g++-13 jq ccache, ubuntu-22.04, gcc-13, 17, test/x3, gcc-13)	10m 27s
posix (STD=11 JOB=test/qi, boost, clang-14 libc++-14-dev libc++abi-14-dev libunwind-14-dev jq cc...	8m 23s
posix (STD=11 JOB=test/karma, boost, clang-14 libc++-14-dev libc++abi-14-dev libunwind-14-dev jq...	7m 52s
posix (STD=11 JOB=test/lex, boost, clang-14 libc++-14-dev libc++abi-14-dev libunwind-14-dev jq c...	6m 19s
posix (STD=11 JOB=test/support, boost, clang-14 libc++-14-dev libc++abi-14-dev libunwind-14-dev ...	2m 19s
posix (STD=11 JOB=repository/test, boost, clang-14 libc++-14-dev libc++abi-14-dev libunwind-14-d...	2m 29s
posix (STD=11 JOB=test/qi, boost, g++-11 jq ccache, ubuntu-22.04, gcc-11, 11, test/qi, gcc-11)	7m 6s
posix (STD=11 JOB=test/karma, boost, g++-11 jq ccache, ubuntu-22.04, gcc-11, 11, test/karma, gcc...	6m 34s
posix (STD=11 JOB=test/lex, boost, g++-11 jq ccache, ubuntu-22.04, gcc-11, 11, test/lex, gcc-11)	4m 59s
posix (STD=11 JOB=test/support, boost, g++-11 jq ccache, ubuntu-22.04, gcc-11, 11, test/support,...	2m 18s
posix (STD=11 JOB=repository/test, boost, g++-11 jq ccache, ubuntu-22.04, gcc-11, 11, repository...	2m 22s
	1h 6m 3s

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