He breaks 2 strings a night for 6 nights for a total of 2*6 = <<2*6=12>>12 broken strings

He breaks 12 strings per week so over 12 weeks, he will need to replace 12*12 = <<12*12=144>>144 guitar strings

# Answer

144
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Dave breaks 2 guitar strings per night when playing live.  If he performs 6 shows a week for 12 weeks, how many guitar strings will he need to replace?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
144
Dave breaks 2 guitar strings per night when playing live.  If he performs 6 shows a week for 12 weeks, how many guitar strings will he need to replace?
train