Adding machines

My father was an accountant (who became a missionary accountant/business manager), and on his desk sat an electric mechanical adding machine. It only let you enter about 9 digits (may have been 8), but of course if you added 9,999,999.99 and .01 you'd get the proper 10,000,000.00. It did 1 digit overflows fine. Did it do 2-digit overflow? I added 9,999,999.99 eleven times, and yes -- it did account for 2-digit overflows.

How about 3-digit overflows, for 12 digits total? I bobbled that test the first time -- I lost count and didn't type enough entries -- but the second time I typed in all 101 entries and hit the "enter."

It only gave the 11 digits. Phooey.

Worse, I must have bent something, because ever after, if you rested your finger on the "enter" key too long, it would not just print the current answer, but would follow it with one or more irrelevant lines of 9,999,999.99

Since he included the adding machine tape in the records, this may have confused whoever looked at the records later.