Keywords by type

Arithmetical operators
+ - / * () !
MOD

Mathematical constants
PI, e

Mathematical functions
SIN, COS, TAN, ASIN, ACOS, ATAN, LN, POW, SQRT, INT
RND

String functions that return a numerical value
LEN, VAL, ASCII, INSTR, VALLEN

Statements
PRINT, LET, DIM, IF, GOTO, INPUT, REM, FOR, NEXT

Auxiliary keywords
THEN, AND, OR, TO, STEP

Functions that return a string
CHR$, STR$, LEFT$, RIGHT$, MID$, STRING$