Articles

Find your generation by birth year. See the Pew ranges for Boomers, Gen X, Millennials and Gen Z, why cutoffs differ, and how cusp years work.

Learn how to write numbers in words: grouping digits in threes, hyphens for 21 to 99, US vs UK and, check amounts with cents, and short vs long scale.

CTR is clicks divided by impressions; conversion rate is conversions divided by clicks. Learn both formulas, the funnel rate, and the traps.

Lumens measure total light output; lux measures light per square meter on a surface. Learn the formula, foot-candles, and the inverse-square law.

Multiply jar fluid ounces by 0.85 to get wax weight. See the six-jar worked example, fragrance oil per pound, and how to size odd jars.

Learn how to calculate lye for soap: SAP values, superfat, water and lye concentration, NaOH vs KOH, blends, and safe lye handling, with worked examples.

How much sand do you need? Multiply area by depth, divide cubic feet by 27 for cubic yards, then about 1.35 tons per yard. Depths for pavers and play areas.

Work out water tank capacity for box and round tanks, convert cubic meters to liters and gallons, handle partly full horizontal tanks, and find usable volume.

Steel weight is volume times density. Learn the formula for round bar, flat plate and pipe, the 7,850 kg/m^3 rule, and the d^2/162 rebar shortcut.

Find a matrix inverse step by step: the 2×2 swap, negate and divide recipe, the determinant test, 3×3 Gauss-Jordan, and solving Ax = b.