I frequently get annoyed by reports in the media that one thing is, for example. three times greater than another. What does that mean? Three times what?

If it is said that John is three times older than Mary, and Mary is, say, 20, then how old is John? If we said John is 40 years older than Mary, then we would add (20 + 40) so he would be 60. So, as three times Mary’s age (3 x 20 =60), we should add that to Mary’s age, and get 80. But I suspect that what is really meant is that John’s age is three times Mary’s, so he would be 60.

That could be regarded as mere pedantry. But things get worse if we consider less/younger/smaller etc. If “Mary is three times younger than John” what does that actually mean? Three times what? If we agree, as above, that Mary is 20 and John is 60, then 3 x Mary’s age = 60, subtract that from John’s age, and Mary is 0 years old. Even worse, 3 x John’s age = 180 and Mary is minus 160 years old!

Even the respected scientific journal *Nature* is not immune. I recently came across the statement that a new solar probe will reach seven times nearer to the sun than any previous probe, and I am completely at a loss as to what they actually mean.