Calculating infusion completion times

0 An IV started at 2250 is to complete in 4 hr 20 min. Calculate the completion time.
2250
420
_______
2670
Change the 70 min to 1 hr 10 min=2710
Deduct 24 hr from 2710=0310 I don't understand this right here at all. How did it go from 2710 to 0310 can someone explain to me?? 

Jan 22, '13 by KelRN215, BSN, RNQuote from EmilyEmily22:50 is 10:50 PM. There is no such time as 27:10 because there are only 24 hrs in a day.An IV started at 2250 is to complete in 4 hr 20 min. Calculate the completion time.
2250
420
_______
2670
Change the 70 min to 1 hr 10 min=2710
Deduct 24 hr from 2710=0310 I don't understand this right here at all. How did it go from 2710 to 0310 can someone explain to me??
Honestly, you're making this more complicated than it needs to be. You add four hours to 22:50 and that takes you to 02:50. Twenty more minutes takes you to 03:10. 
Jan 24, '13 by nurseprnRNIt's a twentyfour hour clock.
Midnight is 0000 (or sometimes 2400)
One minute past midnight is (always) 0001
One am is 0100
two fifteen am is 0215
six am is 0600
Noon is 1200
One minute past noon is 1201
One pm is 1300
six pm is 1800
seven forty five pm is 1945
nine pm is 2100
Sometimes whole hours are just two digits, 01, 05, 10, 14, 21... etc.
This eliminates confusion between am and pm in charting. 
Jan 27, '13 by brat514Quote from EmilyEmilyFor me, the easiest would be to add the 420 to the time it was started: 2250 + 420 = 2670. Once you get the 2670, then you will subtract 2400 (since you're working off of a 2400 clock) so 2670  2400 = 210. So 0210 (2:10 am) would be the completion time.An IV started at 2250 is to complete in 4 hr 20 min. Calculate the completion time.
2250
420
_______
2670
Change the 70 min to 1 hr 10 min=2710
Deduct 24 hr from 2710=0310 I don't understand this right here at all. How did it go from 2710 to 0310 can someone explain to me??
Hope it helps! 
Jan 27, '13 by nurseprnRNOopsy, brat514. 2670  2400 is not 210. It's 270, which is, in military time, 0310, ten past three am.
Try using a clock face to look at this problem. You have a start time and a duration of four hours and twenty minutes.
Start at 2250, 10:50 pm, ten minutes before 11pm.
Add twenty minutes: 11:10 pm. Add four hours. 3:10 am. Done. Kel had it right, and you should look at her arithmetic to see where she got it right and you missed it. There will be a lot of these questions in your future.

Jan 28, '13 by brat514Quote from GrnTeaThank you grntea! Ya know, I had posted 0310 at first then overthought it and edited it. Oops!Oopsy, brat514. 2670  2400 is not 210. It's 270, which is, in military time, 0310, ten past three am.
Try using a clock face to look at this problem. You have a start time and a duration of four hours and twenty minutes.
Start at 2250, 10:50 pm, ten minutes before 11pm.
Add twenty minutes: 11:10 pm. Add four hours. 3:10 am. Done. Kel had it right, and you should look at her arithmetic to see where she got it right and you missed it. There will be a lot of these questions in your future.
To the OP, sorry! I hope I didn't confuse you even more