Anything that involves percentages.
In: Mathematics
a big thing when hearing people talk about percentages is that there can be a MASSIVE difference between “increased *BY* x%” and “increased *TO* x%”. the latter means the chance of something happening is now the new percentage, while the former involves actually calculating what the new value is, and can be tricky or even scary if one doesn’t know about the difference
the most common example I see used is those phrases thrown around that go like ‘having a baby after 45 increases deformities by 80%!’ which at first glance sounds super scary, right? that’s a ton of babies! except that the chance increases BY 80%, not TO 80%. so, say that before mom is 45, chance of those things happening equates to 1% of births (1 in 100, just throwing out a basic number for easy math here). 80% is equivalent to 80/100, or 0.8. you’re adding 80% of the original number to the number to find the new rate, so you would use this:
1 + (0.8 x 1) = 1+0.8 = 1.8
so rather than a big huge number it turns out that for mothers older than 45, a bit less than 2 in 100 babies will have a deformity from the previous 1 in 100.
it can also help to convert to multiplication when figuring out what a percentage means. “per cent” means “of 100” so 100% is equal to multiplying by 1 (100/100), 200% is 2x (200/100), 250% is 2.5x (250/100), 1000% is 10x, etc. basically take the decimal and move it to the left two digits before multiplying the original number by that amount.
“50% more/less” (or other numbers) is common on packaging, but you can equate it to 1.5 and 0.5 respectively (the 1 comes in for the “50% more” because you are adding the original amount to the new amount, you can break this number down to 1x + 0.5x)
tldr, if a Big Bag has 50% more than a Normal Bag, it has the equivalent of 1 1/2 (1.5x) Normal Bags. meanwhile a Mini Bag that has 50% less product is half the amount of a normal bag (0.5x)
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