Help on a summative formula

[Ahimsa Consulting]

Hi all
Need newbie level assistance on putting together a formula. I am trying to
work out the phrasing for reading user input and adding each input to the
previous input until the total is >= 150. I thought for a while the
Fibonacci series might help since that passes the value of one element and
adds it to a previous value, so it worked fine for the first two inputs but
then went off at a tangent.
Any thoughts please.
Thanks
Andrew