A simple program that was tricky on the original MK-52, but easy on the Resurrect:

#
# MK-52 program
#
PC=0000
P0000: LBX> ENTER N.X:
P0001: LBY> MOLAR WEIGHT:
P0002: Cx
P0003: Enter
P0004: STOP
P0005: X->M L0
P0006: M->X L0
P0007: -
P0008: 100
P0009: *
P0010: K M->X L0
P0011: *
P0012: +
P0013: Enter
P0014: GOTO 0004
#
# MK-52 data
#
MC=0001
M0001: 1.008
M0002: 4.0026
M0003: 6.94
M0004: 9.0122
M0005: 10.81
M0006: 12.011
M0007: 14.007
M0008: 15.999
M0009: 18.998
M0010: 20.18
M0011: 22.99
M0012: 24.305
M0013: 26.982
M0014: 28.085
M0015: 30.974
M0016: 32.06
M0017: 35.45
M0018: 39.948
#... and so on through the Periodic table 

Start by pressing B/0, S/P, then enter the <element number>.<number of atoms in molecule>, S/P.

For example, glucose (C6 H12 O6):

B/0, S/P,

6.06,S/P,

1.12,S/P,

8.06,S/P

The same calculation manually (in the most efficient RPN way) looks like this:

12.011 Enter

15.999 +

1.008 Enter

2 * + 6 *,

and each element weight (12.011, 15.999 and 1.008) has to be punched-in. With the program, obviously, still need to keep the Periodic table in hand, but no need to type the numbers with decimal places.