How do I spread a remainning balance of 11 mos gradually upward untill
it is gone with 1 known starting number, and an annual number.

One way (among many possible) is illustrated in the csv file below.

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Annual,10000
Jan,100
Feb,=B2+(B$1-12*B$2)/66
Mar,=B3+(B$1-12*B$2)/66
Apr,=B4+(B$1-12*B$2)/66
May,=B5+(B$1-12*B$2)/66
Jun,=B6+(B$1-12*B$2)/66
Jul,=B7+(B$1-12*B$2)/66
Aug,=B8+(B$1-12*B$2)/66
Sep,=B9+(B$1-12*B$2)/66
Oct,=B10+(B$1-12*B$2)/66
Nov,=B11+(B$1-12*B$2)/66
Dec,=B12+(B$1-12*B$2)/66
Total,=SUM(B2:B13)