Most people use "order of magnitude" to mean "by a factor 10". I've always thought this was inappropriate. The origin of this expression is that the scientific use of magnitude implies a logarithmic scale. But "magnitude" was first used in astronomy with a scale that had a 2.5 base, not a 10 base.
that phrase (for countless years) feels like an attempt to sound precise, but is imprecise. great example there.