[r-t] Doubles Principles

[Mark Davies]

Hugh Pumphrey writes,

> OK, so I just tried 10 changes. Lots of possibilities emerge of which
> 3-1-5-1-3-1-5-1-3-1- is just one. And as it is pure doubles you can
> immediately obtain a 100 with two singles. But I suspect that the remaining 20
> changes are a bit inaccessible.

How about 3-1-5-3-5-3-5-3-5. Pretty easy to get a 120 from that, with 
bob = 125 and single = 145...

MBD