Floats

const std = @import("std");
const math = std.math;

pub fn main() void {
    const a: f32 = 1.5;
    const b: f64 = 3.14159265358979;
    const c: f128 = 1.0 / 3.0;

    std.debug.print("f32:  {d}\n", .{a});
    std.debug.print("f64:  {d:.5}\n", .{b});
    std.debug.print("f128: {d:.10}\n", .{c});

    std.debug.print("sqrt(2) = {d:.6}\n", .{math.sqrt(@as(f64, 2.0))});
    std.debug.print("inf: {d}\n", .{math.inf(f64)});
    std.debug.print("nan: {d}\n", .{math.nan(f64)});
}

The {d} specifier prints a float in decimal form, and {d:.5} gives you five fractional digits.