How to get the total sum

[TPG]

I have data on Column A and B, I would like to total up a sum by multiply A1
to B1, A2 to B2, A3 to B3 and so on. But the sum must appear on the last line
of Column B.
(in this example is B5). Thank in advance.
A B
1. 5.00 25
2. 73.40 48
3. 86.70 60
4. 14.90 237
5. ???

 

[Sheeloo]

Enter this in B5
=SUMPRODUCT((A1:A4)*(B1*B4))

 

[T. Valko]

Try this:

=SUMPRODUCT(A1:A4,B1:B4)