[question removed by moderator[

Shouldn’t the number of periods be (2041-2014+1)*2 = 28*2 = 56? (I did this because I thought that coupons will be paid in 2014 through 2041 including both the years) The official answer uses 54.

Can someone please clarify why this is the case? I’d appreciate any thoughts.

The bond has 15 OCT 2014 as settlement date, so no coupon paid in February nor August of 2014.

You should do (2041-2015)*2+1=53 because the first coupon will be received on 15-FEB-2015 and until 15-FEB-2041 there are 53 periods, inclusive. Since the bond matures on 15-AUG-2041 you are entitled to one more coupon, so totaling to 54.