A puzzling arithmetic error in Maxima



(C185) 57.50+14.95+18.95+8.95+22.95+12.95+7.95+6.95+19.95+12.95+8.95+9.95+
16.95+19.95+11.95;

(D185)                         251.7999999999999

Anybody has an idea why Maxima produced 251.799.... instead of 251.8?

Milan