Answer 1
According to Pierce's Piano Atlas Baldwin pianos have no more than 6 digit serial numbers so maybe the poster has not got the right number. Some pianos have more than one number, but only one is the serial number.
Answer 2
Looks like it was produced around 1987. Baldwin uprights after the mid 1970s have 7 digit serial numbers.
As of November 2013, the age of a Baldwin piano with serial number 246905 would be 32 years old.
According to my copy of the Pierce Piano Atlas, the Baldwin piano with serial number 127398 was manufactured in 1954.
1980
The Baldwin Acrosonic piano with the serial number 835830 was likely manufactured in the late 1950s or early 1960s. Baldwin typically assigned serial numbers to their pianos in a sequential manner, and this particular number falls within the range that corresponds to that time period. For a precise year, you may need to consult a Baldwin piano reference guide or contact a piano technician who specializes in Baldwin instruments.
1986
As of November 2013, the age of a Baldwin piano with serial number 246905 would be 32 years old.
How old is this piano with serial number 1510355
This serial number is not available. I have 278556 ultrasonic Baldwin piano is in 1988.
According to my copy of the Pierce Piano Atlas, the Baldwin piano with serial number 127398 was manufactured in 1954.
1980
1986
207 years
Very old about 209 years old
According to bluebookofpianos.com, an Acrosonic piano with this serial number would have been manufactured in 1964.
Baldwin started manufacturing in 1959 at serial number 655948 and then 1960 at serial number 679844. In that case, the serial number 673394 would belong to a Baldwin piano produced some time in the second half of 1959.
464712
According to the serial number provided, it was built in 1942. According to bluebookofpianos dot com, it was built in 1995.