Wrong, each whole number (one point) is ten times stronger than the previous. A 5.0 in ten times stronger than a 4.0
T Minus Four, that is not true although your comment is based upon a common misconception.
Magnitude is the logarithmic measurement of the amplitude of waves on a seismogram.
When comparing Magnitudes, you are comparing the measurement of amplitude of waves between the two earthquakes. Comparison of Magnitude is not a comparison of strength or energy of the two earthquakes.
It would be correct to say that a 5.0 Magnitude earthquake is ten times bigger than a 4.0 earthquake again, keeping in mind that it is the measured amplitude of waves which are being compared.
A 5.0 earthquake is actually 31.6 times stronger than a 4.0 earthquake. An earthquake's energy is the damaging factor.