Replacing a repeating number in a file with random numbers

I want to replace all occurrences of a number with a random number in each line of a file using "sed". For example, if my file has the number 892 in each line, I would like to replace that with a unique random number between 800 and 900.

Input file:-

temp11;djaxfile11;892

temp12;djaxfile11;892

temp13;djaxfile11;892

temp14;djaxfile11;892

temp15;djaxfile11;892

Expected output file :-

temp11;djaxfile11;805

temp12;djaxfile11;846

temp13;djaxfile11;833

temp14;djaxfile11;881

temp15;djaxfile11;810

I am trying the below:-

sed -i -- "s/;892/;`echo $RANDOM % 100 + 800 | bc`/g" file.txt

but it is replacing all the occurrences of 892 with a single random number between 800 and 900.

Output file :-

temp11;djaxfile11;821

temp12;djaxfile11;821

temp13;djaxfile11;821

temp14;djaxfile11;821

temp15;djaxfile11;821

Could you please help in correcting my code ? Thanks in advance.