The 2.31 is used to convert pressure from pounds per square inch into feet of water (column). This conversion is useful when dealing with pumps.
Feet divided by 5,280 = miles
5280/1 mile
1mile/5280feet
I suggest you convert the feet to inches (or vice versa, convert the inches to feet - but converting the feet to inches is easier), then it will be easy to compare the two measurements.
The large value converting to small value is multiplied. The small value converting to large value is divided. inches (small value) to feet (large value) is divided. The number of inches in a feet is 12 inches, so to convert inches to feet, one would need to divide the number by 12.
4.92125984 feet ==
feet = cms ÷ 30.48
Feet divided by 5,280 = miles
Multiply the number of km by 3,280.839 to get feet.
Multiply feet by 12
Meters times 39.3701 = feet
Divide feet by three to get yards.
99 inches = 8.25 feet
4.11 feet is 1.25 meters.
3 feet equal 1 yard
Here it is: miles x 5,280 = feet
1 nautical mile = 6076.12 feet.