HI Tracy,

=FV(5%/12,30,30,-900)

Look at Future Value (FV) in Help
Remember to use rate =5%/12 and for nper use 30 (months)
PV is you initial amount -900  (negative since you GAVE the money to the
bank)
PMT is +30 since (positive since you GOT the money)
I get $63.02 which agrees with an amortization table I made

0   900               ( 0 in A1, 900 in B1 - starting about a month zero)
1   =A1*(1+5%/12)-30                    (interest after first month less
withdrawal)
2  =A2*(1+5%/12)-30
....
30 =A30*(1+5%/12)-30

best wishes

Actually the interest is always going forward.  Let's say that at the end of
the first month, monthly interest is first accured on the $900, and then 30
is withdrawn.  At the end of the second month, monthly interest is accured on
the balance at the end of the first on and then 30 is withdrawn.

The two main ways of calculating the interest rate are:

YearlyRate/12
and
(1+YealyRate)^(1/12)-1

Let's look at both ways.  In both B1 and B1 enter:
900

In A2 enter:
A1*(1+0.05/12)-30 and copy down

In B2 enter:
=B1*(1+0.05)^(1/12)-30 and copy down

We see:

900    900
873.75    873.6667114
847.390625    847.2261377
820.9214193    820.6778419
794.3419252    794.021385
767.6516832    767.2563264
740.8502319    740.3822237
713.9371079    713.3986325
686.9118458    686.3051068
659.7739785    659.1011988
632.5230367    631.7864587
605.1585494    604.3604349
577.6800433    576.8226741
550.0870435    549.1727211
522.3790729    521.4101187
494.5556523    493.5344081
466.6163009    465.5451284
438.5605355    437.4418168
410.387871    409.224009
382.0978205    380.8912382
353.6898948    352.4430363
325.1636027    323.8789328
296.518451    295.1984557
267.7539445    266.4011307
238.869586    237.4864819
209.8648759    208.4540313
180.7393129    179.3032988
151.4923934    150.0338026
122.1236117    120.6450589
92.63246007    91.1365818
63.01842865    61.50788352