The numbers below are minimal thresholds to achieve a letter grade, hence in the 1000pt scale, you need an 800 to get a B-. 799.999 does not reach this threshold and consequently is a C+.
100 pts 1000 pts A 93 A 930 A- 90 A- 900 B+ 87 B+ 870 B 83 B 830 B- 80 B- 800 C+ 77 C+ 770 C 73 C 730 C- 70 C- 700 D+ 67 D+ 670 D 63 D 630 D- 60 D- 600 F< 60 F< 600
I know grades can be disappointing. I wish I didn't have to bother with them as I explain in a blog posting about The Travail of Grading.