Hmm ... It's impossible ;-) This RPM doesn't exist on any FTP server

Provides :
crate(num-rational/std)
rust-num-rational+std-devel

Requires :

(crate(num-bigint) >= 0.4.0 with crate(num-bigint) < 0.5.0~)
(crate(num-bigint/std) >= 0.4.0 with crate(num-bigint/std) < 0.5.0~)
(crate(num-integer/std) >= 0.1.42 with crate(num-integer/std) < 0.2.0~)
(crate(num-traits/std) >= 0.2.18 with crate(num-traits/std) < 0.3.0~)
cargo
crate(num-rational) = 0.4.2
rpmlib(CompressedFileNames) <= 3.0.4-1
rpmlib(FileDigests) <= 4.6.0-1
rpmlib(PayloadFilesHavePrefix) <= 4.0-1
rpmlib(PayloadIsZstd) <= 5.4.18-1
rpmlib(RichDependencies) <= 4.12.0-1
rpmlib(TildeInVersions) <= 4.10.0-1

Content of RPM :
/usr/share/cargo/registry/num-rational-0.4.2/Cargo.toml