Rule: Each letter in the word is replaced by its position in the English alphabet. Then all values are multiplied together.

Positions: N = 14
O = 15
T = 20
E = 5
S = 19

Step-by-step: NO = $14 \times 15 = 210$
NOT = $14 \times 15 \times 20 = 4200$
NOTE = $14 \times 15 \times 20 \times 5 = 21000$
NOTES = $14 \times 15 \times 20 \times 5 \times 19 = 399000$

Hence, the correct answer is 399000 (Option A).