∑ RPN
HP-style stack calculator. Enter pushes, ops pop. Try: 3 [enter] 4 [+] 2 [*]. Memory M+, M-. SUM averages stack.
7
8
9
+
−
4
5
6
×
÷
1
2
3
^
%
0
.
⏎
±
C
DROP
SWAP
DUP
√
1/x
sin
cos
tan
ln
log
π
e
SUM
AVG
STD