• thisfro@slrpnk.net
      54·
      11 months ago

      They probably did, just not explicitly:

      You could write (6*1/100)*50 = 6*(50*1/100)

      It only uses the commutative property of multiplication and the fact that % is another way of writing 1/100.

      Maybe also worth remembering that “x% of y” is just x/100*y

        • Ravi@feddit.de
          20·
          11 months ago

          The word percent is exactly that per cent, which basically means parts of hundred. E.g. 10% are 10 of 100, or 60% are 60 of 100. You can also write this mathematically as 60/100 or 60÷100, which is 0.6.

          Now in general: x% are x parts of 100 or x/100 or x÷100. If you want to calculate x% of y you just multiply it: y × x% = y × x ÷ 100.

  • jasondj@ttrpg.network
    481·
    10 months ago

    Idk if it’s the weed, the adderall, or the ADHD, but this thread is everything I need in my life.

      • jasondj@ttrpg.network
        3·
        10 months ago

        Honestly I recently switched to vyvanse and I don’t actually smoke to get high (at least not until the kids are in bed). I just microdose a bit throughout the day and it balances out the vyvanse. Like, the stimulants alone are just a little bit too much for me. The combo, though, I can dial in just right.

        But weed alone always made me fixate on arithmetics. And then stims turn that up to 11.

  • Marxism-Fennekinism@lemmy.mlEnglish
    111·
    10 months ago

    Also, a surprising number of people don’t know that precentages are more often than not represented as decimals between 0 and 1 as opposed to actually a number out of 100 when used in calculations (because the concept of a percent doesn’t really exist in math, it’s just a context specific way of formatting a decimal). A lot of people just enter 69 when calculating a formula that operates on a precentage instead of 0.69 which obviously makes the formula useless, or if a formula is supposed to output a precentage, they assume that it output 0.69 percent instead of 69 percent.

  • cmhe@lemmy.world
    129·
    10 months ago

    I thought with “reversible” they meant that a number falling 50% and then rising 50% afterwards, it is the same number, which is not true.

    10 * 50% = 5

    5 * 150% = 7.5

    • Sylvartas@lemmy.world
      2·
      10 months ago

      Yeah the correct term would be “commutative” as someone already pointed out. Meaning the order doesn’t matter when considering multiple percentages. E.g 50% of 73% of something is the same as 73% of 50% of that same thing

    • GBU_28@lemm.eeEnglish
      0·
      11 months ago

      You can multiply by 9 on your fingers.

      Hold hands out, fingers splayed, thumbs towards each other. 🙌

      9*2 put your left ring finger down (the 2nd finger). Left of that is tens place, right of that is the ones place.

      So 1 on the left, 8 on the right of the downed finger.

      9*5 put the left thumb down (5th finger.) 4, 5. 45.

      • n0m4n@lemmy.world
        1·
        10 months ago

        The trick that I teach the shorter humanoids is to subtract 1 from the multiplier of 9, put that number in the 10s column, then complete the nine and put that in the 1s column.

        Then we spent some time finding the pairs of numbers that make 9. 1+8. 2+7, 3+…7+2, 8+1. I have to be explicit in this part, or they will shortcut to 3, (use fingers to count to 9) uh 6? They usually learn it in a day or two. To get them to flash to instantly know their times tables takes longer.