@QvQ There is no shortage of coffee if you go to the right store. You just need to go to a Walmart or Costco or other larger chain that has coffee that isn't the one you've used.
To calculate gasoline cost in just seconds,
round your numbers to a nearby approximate number.
Gasoline at $3.85 or $4.20 we will just round to the nearest 50cent number -- so we round that those to just
$4/gallon (current national average is $3.98).
So just use $4 --
it's close enough to get a useful result.
If the one-way trip to a Costco or Walmart or other cheaper store is 45 or 54 miles,
you'd just round to the closest 10 -- so, I'd round it 50 miles -- it's close enough to give an approximate number.
If your car gets 18 miles per gallon (MPG) or gets 22 (MPG),
you just round it to the closest 5 -- so, here we take 20 mpg -- it's close enough to give an approximate number.
So, you use close enough numbers, which makes it easy to do in your head.
If our distance to
Walmart is 1 way 50 miles, we just multiply by 2 for the full trip there and back, which in this example is then 100 miles.
So, for a close to 20 mpg car, that round trip would use up
5 gallons.
5 gallons at $4/gallon is about $20.
You can do this in just seconds. Any day.
After you have done this just once (use a calculator if you need), then you can quickly use the same number again when gasoline changes with just 1 single multiplication.
Suppose that 1 month later gasoline is closer to $4.50 -- you'd just take the number you already know: we got $20 above in our example for when when gas was about $4, and just multiply that old $20 cost by the new gas price divided by the old gas price.
So, 4.50/4.00 is the same as 9/8 == so that's an increase of about 1 part in 8.
So, the gasoline trip cost that was $20 is now $20 plus 1/8th of $20. We don't want to work hard, so you can just realize that 8 goes into $20 about 2 or 3 times....
That number: 3 (we will use the higher one) is the increase in cost.
So, for closer to $4.50/gallon gasoline, that old trip that cost $20 will now cost about $23.
If you really want high precision you would add about 20 cents per mile for maintenance costs over time (this high number is for an older car that needs more maintenance: 20 cents/mile). So, for a 100 mile round trip, that's $20 extra for the wear and tear on the car.
So, the basic full cost of both gas and maintenance is then about $40 for the trip. That's why I pointed out that at least $50 of savings is what I'd need to see to make that trip. It's a special once a month trip meant to buy a lot of stuff cheaper than you usually buy nearby.
Suppose you get unlucky and that 100 mile round trip Walmart store
didn't have coffee -- well, you'd still save on all the
other stuff you needed.