• plague-sapiens@lemmy.world
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      1 year ago

      Its easier:

      10% of a 100: 100 * 0,1 = 10

      2,5% of 33: 33 * 0,025 = 30 * 0,025 + 3 * 0,025 = 0,75 + 0,075 = 0,825

      Thats how I calculate it mostly in my brain. But being smart I usually just type everything (like 9*9) in the calculator xD