On the third day, there were one-third of the number of bedbugs as the fourth day, so there were 810 / 3 = <<810/3=270>>270 bedbugs.

On the second day, there were one-third of the third day’s bedbugs, so there were 270 / 3 = <<270/3=90>>90 bedbugs.

On the first day, there were 90 / 3 = <<90/3=30>>30 bedbugs in the group to start with.

# Answer

30
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
A group of bedbugs infested an old mattress. Every day, the number of bedbugs would triple. After four days, there were 810 bedbugs burrowing into the mattress. How many bedbugs did the group start with?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
30
A group of bedbugs infested an old mattress. Every day, the number of bedbugs would triple. After four days, there were 810 bedbugs burrowing into the mattress. How many bedbugs did the group start with?
train