[Mental Math]

Here is a cool trick to add hours and minutes together:

Let's try adding 3 hr 23 minutes and 2 hr 46 minutes together.
Make the 3 hr 23 minutes into one number, which will give us 323 and do
the same for the other number, 2 hours 46 minutes, giving us 246.
Now add these two numbers together:

323
246
569

So, we have a total of 569.
Now, if the last 2 digit is equal to or greater than 60, just add 40 to the total, otherwise keep it as it is.

569 + 40 = 609

And now, split the number to get the answer which is 6 hrs and 09 minutes!

This post has been edited by swansont: 27 January 2012 - 08:45 PM
Reason for edit: remove url

[DrRocket]

quaes, on 27 January 2012 - 06:31 PM, said:

Here is a cool trick to add hours and minutes together:

Let's try adding 3 hr 23 minutes and 2 hr 46 minutes together.
Make the 3 hr 23 minutes into one number, which will give us 323 and do
the same for the other number, 2 hours 46 minutes, giving us 246.
Now add these two numbers together:

323
246
569

So, we have a total of 569.
Now, if the last 2 digit is equal to or greater than 60, just add 40 to the total, otherwise keep it as it is.

569 + 40 = 609

And now, split the number to get the answer which is 6 hrs and 09 minutes!


Mental Math With Tricks & Shortcuts

Isn't rather a lot easier to just note that 46 minutes + 23 minutes = 1 hour and 9 minutes, do the remaining 3 + 2 quickly in your head, and go have a beer ?

[swansont]

!

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[khaled]

I'd think about modulus 60 in modular arithmetic, or to make seconds & minutes in Base 60 ...