How to Use Sin, Cos, Tan and Their Inverse Functions on a Calculator
Learn what sin, cos and tan mean, how to compute them on a calculator, and how asin, acos and atan reverse the process to find an angle.
Articles
Why Do Calculators Sometimes Show a Slightly Wrong Decimal?
A calculator showing 0.30000000000000004 instead of 0.3 is not broken. Learn the plain-language reason binary math rounds some decimals.
How Does the Percent Button Work? Discounts, Tips and Percentage Change
The percent key does not behave the same on every calculator. Learn the exact formulas for discounts, tips, and percentage change, with worked examples.
Why Does 1 + 2 x 3 Equal 7? Calculator Order of Operations Explained
Type 1 + 2 x 3 into a calculator and the answer is 7, not 9. Learn the order of operations rule behind it, and how to force any order with parentheses.
Degrees vs Radians: Why Your Calculator Gives the Wrong Trigonometry Answer
Same button, two different answers. Learn why calculator mode changes every trig result, how to spot degrees vs radians, and how to convert between them by hand.
What Do MC, MR, M+ and M- Mean on a Calculator?
Learn exactly what MC, MR, M+ and M- do on a calculator, plus a worked example that adds three subtotals to find a total fast.
Turkey Cooking Time by Weight
A general turkey roasting time chart by weight, from 12 to 24 pounds, plus the real safe internal temperature and how long to rest and thaw the bird.
How Much Rice or Pasta Per Person?
Learn how much dry rice or pasta to cook per person, how portions change for sides versus mains, and how to scale amounts for a group of 8.
The Perfect Coffee-to-Water Ratio
Dial in your coffee with the golden ratio and brew-method adjustments. Learn how to measure by weight, convert a ratio into a real recipe, and adjust to taste.
Common Ingredient Substitutions
Swap ingredients with confidence. See exact substitution ratios for baking soda, buttermilk, eggs, butter, sugar, and more, plus when not to substitute.