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Numbers & Conversions?

Cups, miles, percentages. The stuff you re-Google forever. 22 questions and counting.

How many cups are in a gallon?16 cups in a gallon. The full ladder: 2 cups to a pint, 2 pints to a quart, 4 quarts to a gallon. Everything doubles, wh…
How many feet are in a mile?5,280 feet. The odd number is Rome's fault mixed with England's: a Roman mile of 5,000 feet got stretched to fit exactly…
How do you calculate a percentage?Part divided by whole, times 100. And for mental math, flip stubborn ones: x percent of y equals y percent of x, so 4 pe…
How do you convert Celsius to Fahrenheit?Exact: multiply by 9/5 and add 32. Fast enough for weather: double it and add 30. And the anchor points to memorize: 0C …
What is a prime number?A whole number greater than 1 divisible only by 1 and itself: 2, 3, 5, 7, 11. They are the atoms of arithmetic, there ar…
How many weeks are in a year?52 weeks plus one extra day, or two in a leap year. That leftover day is why your birthday shifts one weekday each year,…
What is the order of operations?Parentheses, exponents, then multiplication and division left to right, then addition and subtraction left to right. The…
What is pi, and why does it matter?The ratio of any circle's circumference to its diameter, about 3.14159, and it is the same for every circle regardless o…
What is the difference between mean, median, and mode?Mean is the average, median is the middle value, mode is the most common. Median beats mean whenever a few extreme value…
How do you calculate a tip in your head?Move the decimal one place left for 10 percent, then add half of that for 15 or double it for 20. On a $46 check: 10 per…
What does average annual return actually mean?Usually the compound annual growth rate, the steady rate that would produce the same end result, not the simple average …
How do you read a nutrition label?Start with serving size, because every number below it is per serving, not per package. Then check added sugars and sodi…
How much bigger is a trillion than a billion?A thousand times bigger, which is nearly impossible to feel. In seconds: a million is about 12 days, a billion is about …
What does statistically significant actually mean?That a result is unlikely to have arisen by chance alone under the assumption of no real effect, conventionally at a p-v…
How do you convert fractions to decimals and percentages?Divide the top by the bottom to get the decimal, then multiply by 100 for the percentage. Three quarters is 3 divided by…
What is the difference between weight and mass?Mass is how much matter something contains and never changes; weight is the force gravity exerts on that mass and change…
Why is a day 24 hours and an hour 60 minutes?Egyptians split day and night into 12 parts each, likely using a base-12 counting system on finger joints. The 60-minute…
What is a good credit score?On the common 300 to 850 scale, roughly 670 and up is good, 740 and up is very good, and 800 and up is exceptional. Paym…
What is the rule of 72?Divide 72 by an annual growth rate to get the years it takes to double. At 6 percent, money doubles in about 12 years. I…
How do you calculate square footage?Multiply length by width for each rectangular section and add them together. For odd shapes, break the room into rectang…
What does margin of error mean in a poll?The range within which the true value probably falls due to sampling alone, usually at 95 percent confidence. A 3-point …
How do you fairly split a restaurant bill?Split evenly when orders are similar and it saves everyone time. When one person had an appetizer, two drinks, and the s…