Throughout my life, I read a "60% increase in x" as $ 60\% * x + x $. For example, if a question asked, "If the initial value of Gold was $39, 162 and if it increased by 50%, what is the price now?", I'd add 50% of 39,162 to get 58, 743.
Now, if I was asked to describe this change, I'd say "The price of Gold increased by 50%". Recently, while I was going through the manual of a calculator though, it said this:
That is, it is describing the "incease in weight" as a 160% increase -- while to me it's just a 60% increase ($ \frac {300}{500} = 0.6 $). What is right terminology to use? To me, a 160% increase is not the same as a 60% increase. It'd make more sense to say that it changed by 160%.
Are both terminologies accepted (increased by 60% vs increased by 160%)? If so, how do we avoid confusion?
The manual is wrong. In the example given in the question, the percentage change is 60%, not 160%.
(Credts: users KM101 and Jens in the comments).