this post was submitted on 25 Jun 2026
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Funny

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[–] rockSlayer@lemmy.blahaj.zone 8 points 1 day ago* (last edited 1 day ago) (6 children)

$7.83

My method:

  • 42.17 + 8.00 = 50.17
  • 8 - 1 = 7
  • 0.17 - 0.02 = 0.15
  • 0.85 + 0.15 = 1.00
  • 0.85 - 0.02 = 0.83
[–] Holytimes@sh.itjust.works 2 points 9 hours ago

My method. 0

Just order to go. Eating at home is comfier

Three cents to $42.20

Eighty cents to $43.00

Seven dollars to $50

Seven eighty-three!

[–] lung@lemmy.world 8 points 1 day ago (1 children)
[–] rockSlayer@lemmy.blahaj.zone 2 points 1 day ago* (last edited 1 day ago) (1 children)

What's the problem with this method? I figure out tips through mental math, without any paper. This is just explaining how I do that mental math

[–] lung@lemmy.world 1 points 1 day ago* (last edited 1 day ago) (1 children)

Yeah you did it in the hardest way possible hahaha

Just subtract 17 from 100 to get the cents. 83. There, done. Or at least 100 - 10 - 7

[–] rockSlayer@lemmy.blahaj.zone 3 points 1 day ago

I can't do mental math that easily. I struggle with visualizing it, I think better in multiples of 5, and subtraction is more intuitive to me

[–] farmgineer@nord.pub 2 points 1 day ago* (last edited 1 day ago)

Mine:

  • ends in not 00, so add whatever makes the ones digit a 9 (7 in this case).
  • make the cents even -> .20 (add .03)
  • go to 100 (add .80)

I think, anyway. I can mostly just look at it and know.

[–] Imgonnatrythis@sh.itjust.works 2 points 1 day ago (1 children)
[–] rockSlayer@lemmy.blahaj.zone 2 points 1 day ago (1 children)

This is how I do mental math. Figuring out (100-15)-2 is a lot easier than 100-17

For me 100-20+3 is easier, but yeah

[–] nialv7@lemmy.world 2 points 1 day ago (1 children)
[–] rockSlayer@lemmy.blahaj.zone 5 points 1 day ago

I used to do calculators for tips, but noticed my mental acuity slipping. I started calculating tips in my head to keep myself sharp