Set a 2.9cm saw x 1 segment and a 4.9cm saw x2 segment, and then list the mathematical model:

Minimum w = 27.9-2.9x1-4.9x2.

Science and technology.

2.9x 1+4.9x 2+0. 1 *(x 1+x2- 1)& lt； =27.9

X 1, x2 is an integer.

The solution is x 1= 1, x2=5, w = 0.5cm.

Therefore, 2.9cm has 1 saw, and 4.9cm has 5 saws to minimize waste.