In the air, Mach 1 decreases with altitude from roughly 760 mph (340 m/s) at sea level and 15 'C to about 660 mph (295 m/s) at 36,000 feet to 66,000 feet (11 000 m to 20 000 m) and -57 'C (cruising altitude of commercial jets).
So 0.85 times that amount gives Mach 0.85 ranging from 646 mph to 560 mph.
Mach 0.85 = about 630.3 mph
889 mach is approximately 683,781.4 mph.
Mach 3 is 2283.6211 mph because Mach 1 equals 761.207033 mph.
Mach 4 is about 3,045 mph
Mach 10 = 7,612.07 mph
Mach 1.7 is about 1,260.6 mph
Mach 63 is about 46,717.3 mph
Mach 3 = 2283.6211 mph
1,750.8 mph
Mach 500 = 380 603.525 mph
Mach 1.6 = 1,217.9 mph
Mach 6 is about 4,449.3 mph
Mach 0.8 = about 593.2 mph