IEEE-754 allows "decimal floats". Basically, instead of 2^exponent, it's 10^exponent. `decimal32`[0], `decimal64`[1], and `decimal128`[2] are defined. But I'm not aware of any popular system that implements them.

[0]: https://en.wikipedia.org/wiki/Decimal32_floating-point_forma...

[1]: https://en.wikipedia.org/wiki/Decimal64_floating-point_forma...

[2]: https://en.wikipedia.org/wiki/Decimal128_floating-point_form...