When someone asks you to add 48 + 27, what happens in your head?

213 Replies

Originally posted by @Joshua D. :

@Jim K.

I would take the 23 and subtract 7 and then multiply by 4 to get the approximate square footage of my yards seasonal rain fall in the post monsoon quadrant...

But on a more serious note I would just take out my phone and use the calculator. Cuz I HATE math...

That and four twenty-four will get you a bagel and schmear at Dunkin' Donuts.

Originally posted by @Dennis Wayne :

I take 48 then add 30 to get 78 then I just subtract 3 because I used 30 number instead of 27

This sounds crazy but it’s much much faster in my mind to do math this way

Just like me with three days and three hours. It's a no-brainer. You think straight into multiples of 10 instead of 5.

There's a pattern here, Denny.


I thought I was going to be the only one. I’m with Dennis. I take the larger number and then round the 2nd number to the nearest 10 and then add or subtract the remainder. That method has gotten me pretty quick at mental math over the years.

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