Quicker Maths

Posted on November 9, 2011

Have you ever faced any problem in adding time?

If you have ever have faced the slightest difficulty in adding time or duration expressed in hours and minutes, this trick is meant for you.

Say you have to add 4 hours 55 minutes and 2 hours 40 minutes.

Make 4 hours 55 minutes into one number, which will give us 455 and do the same for the other number, 2 hours 40 minutes, giving us 240.

Shortcut Trick to Add Two Numbers

Simply add these two numbers together:

455

240

------

695

What you need to do is add 40 to the above result. No matter what the hours and minutes are, just add the constant 40 to the total obtained by adding the time in above manner.

695 + 40 = 735; this means 7 hours 35 minutes.

Be Careful

If there is no carryover from minutes to hours and the minutes digits are less than 60, don't add 40. What you get after first step is your final answer. Say for example, if you have to add 2 hours 20 minutes and 3 hours 35 minutes:

220

335

------

555

So you straight away get your answer as 5 hours 55 minutes.

Another Illustration

Similarly, if someone is coming after 3 hours 55 minutes and right now the time is 1:35PM, you can use the above method to find the time of arrival.

355

135

-----

490

Adding 40 + 490, we get 530. Hence the person will arrive at 5:30PM.

More than two duration

This method can easily be extended for adding more than two time/duration.

So say for example, if you have to add 3 hours 40 minutes, 2 hours 25 minutes and 1 hour 55 minutes, we can do it like this:

340

225

155

------

720

Adding 40 twice to 720, we get 800. Hence, the answer is 8'o Clock.

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#### Posted by Vineet Patawari

1. what for 3:45 + 2:30 + 2:50

2. nyc tricks

3. thanx u 4 dis tricky trick i;ve been looking 4 the methods of adding n subtracting times

4. ???? ???? ?????? ????? ????? ???? ?????? ????? ????? ????? ?? ?? ????? ????? ???? ???? ??? ????? ? ?????? 3 ? 20 ???? ? 2 ? 50 ???? ?? ?? ?????? ?? ??? 320+250+40= 610 ????? 6 ? 10?? ?????? ???? ?? “????? ??? ?????” ?????? ?? ?? ????? ?? ??? ???

5. Sir,
I was using the trick & tried on several examples but I was struck to one where I got total of last two digits as 60 ex-
340
+265
+155
———
760
now should I take it as 8.00?

• U must add 40 twice time as the duration is more than two….

• if there are additions of five times then how much will be the addition of 40 if the answer is 765

• 7:60+40+40= 840 = 8:40

• Hi Pallavi,

You were adding 265 and 155. now please tell mw what is 265? either it should be 2.59 or 3.05.

Rgds/Ramanaiah

• Is 1.345 meter is correct ? No. because we always write meter and centimeter in different position i.e. 345 cm will be written as 3 meter and 45 cm. So 1.345 meter is actually 4 meter (3 + 1 meter=4 meter) and 45 cm.
Similarly 265 is may will be written as 305 (65 minutes= 1 hours+ 05 minutes)
(2+1=3 hours)
i.e. three hours and 5 minutes.

• dear there cannot be any time like 2 hours 65 minutes when we talk abt the time or if it is so u make 2 h 65 mts as 3 hours and 5 minutes as 340+305+155=800
Now, as the sum crossed 60 once so add 40 once to 800=840 so the correct time would be 840

6. yes nice and thanks

7. please i had just checked the interesting to do.. just let me give a chance to say on such farmulaes

8. It is very useful. First I was confused about 1.20+1.30=2.50+40= 2.90
Now it is clear.
Thanks..

• no its wrong because when in ur ans minute is more than 60 than only u hav to add 40 ok ohter

9. Thanks…
It was new for me..

10. very useful trick

11. Wonderful

12. nice trick

13. If you have two numbers to add and the last two
digits of the sum are less than 60, you can’t add
the 40.
Example: 2 hours and 15 minutes and 3 hours
and 40 minutes
215+340=355
If you add 40, it will make it 395, which is incorrect.

In your example for three numbers, they should
and not 800.

• Thanks Michael,

I have made the necessary changes in the post above. I appreciate your contribution.

• @michael

215+340 is 555

it’s not 395

read the first instruction with name be carefull

• we can directly add any numbers like 2-15 + 3-40 = 5-55 is ans

and say 3-40+2-25+1-55 =6-120 now if we divide 120 by 60 then maximum quotient is 2 and remainder is zero this means 6+2-00=8-00

now again say 3-42+2-27+1-57 =6-126 now if we devide 126 by 60 then maximum quitent is 2 and remainder is 6 this means 6+2-06=8-06

we can add as much like 2-10+3-15+4-20+5-40=14-85 and by dividing 85 by 60 oraly maximum quotient is 1 and remainder is 25 this means
14+1-15=15-25

• Very Nice Micheal…Tat was very minute thing but u pointed out d thing…It really helped me to grasp the trick…Thanks

14. awesome blossom!!!!~~~~!!!

15. Best Trick ever