0~49% = F =0~149 points

50~59% = C = 150~299 points

60~79% = B = 300~399 points

80~89% = A = 400~549 points

90~100% = S = 550~650 points

Conversion Table
Class Points (z)	Letter Grade	Senshu grade (y)	Formula
0~149	Fail	0~49%	y=(49/149)z
150~299	C	50~59%	y=(9/149)(z-150)+50
300~399	B	60~79%	y=(19/99)(z-300)+60
400~549	A	80~89%	y=(9/149)(z-400)+80
550~650	S	90~100%	y=(10/100)(Z-550)+90