This post is an amended and upgraded copy of a post in the General Discussion posts group, as I think it could be of value to someone who might not see it there.

Just enter into your browser search box a currency conversion, arithmetic or maths expression and it will display the result in the search results area. 

I use Opera, and tried the following search items - I won't list the results, which were all correct.

The calculations seem to be expedited by use of search engine DuckDuckGo.  Similar calculations worked in Opera, Firefox and Maxthon when I loaded DuckDuckGo.
The key  is using DuckDuckGo as your search engine.

Note: in other browsers, and using Google, some worked. but others went to different solvers.

verbatim:

£100 Eur (currency conversion, goes to xe.com)
£100 $ (ditto)

In the following group, all showed the result and opened a calculator
3*4 (simple multiplication)
3/7 (simple division)
ln(4)  (natural log of 4)
log(4*10) (base 10 log, answer included ",10" to indicate log base 10)
sin(pi/7) value of pi, division, and trig)

In the following group, in Opera, Firefox and Maxthon it opens   symbolab.com, and displays the result.
d(x)/dx (differential calculus )
d(x^2)/dx (differential calculus )
d(x^2+x+1)/dx  (differential calculus )
integral x^2.dx (integral calculus )
integral (x^3+4*x) (integral calculus)

If you enter ln(x) it will calculate  and present the natural log of x (log base e), while if you enter log(x) it will present the answer to x, log base 10, the result including " ,10"

The youtube video is : https://www.youtube.com/watch?v=EQdVXPO6vg8, "14 Computer Tricks You Wish You Learned Sooner", by Bright Side.