Gross, Operating and Net Profit: What Each One Tells You
A business can have three different profit figures from the same sales. This guide walks down the income statement and shows which question each one answers.
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Plain-English guides to the numbers in everyday life: how a calculation works, where people go wrong, and which tool to reach for.
Gross Pay vs Take-Home Pay: Where the Difference Goes
Your paycheck is smaller than your salary divided by pay periods. Here is what comes out, why pre-tax deductions cost less than they appear, and how to estimate.
Healthy Weight Range for Your Height: How It Is Calculated
A healthy weight range is a BMI band turned back into kilograms. Here is the arithmetic, a table for common heights, and why a range beats a single ideal number.
Heart Rate Zones: Percent of Max vs Heart Rate Reserve
Heart rate zones turn "how hard am I working?" into numbers. Learn the two common ways to calculate them and why the same percentage can mean two different heart rates.
Hourly or Salaried? How to Compare Two Job Offers Fairly
A $24 hourly wage and a $52,000 salary are not comparable until you count hours and paid leave. Here is a simple method to line them up.
How Big a Sample Do You Need? Sample Size and Margin of Error
Sample size is a trade-off between precision and cost. Here is the survey formula, a worked example, and why bigger is not always better.
How Credit Card Interest Works: Daily Rates and Minimums
Card interest is charged on a daily balance, not a flat monthly fee. A worked example shows how the daily rate works and how long minimum payments really take.
How Loan Amortization Works: Where Each Payment Goes
Every payment on a fixed loan is the same size, but the split between interest and principal keeps changing. Here is how that schedule is built and read.
How Many Bricks or Blocks Do You Need for a Wall?
A wall needs a fixed number of bricks or blocks per unit of area once you include the mortar joint. Work that number out once and the rest is multiplication.
How Much Concrete Do You Need? Slabs, Footings and Post Holes
Concrete is bought by volume, and every shape reduces to length times width times depth. Here is how to get the number, turn it into bags, and avoid ordering short.
How Much Paint Do You Need for a Room? A Step-by-Step Method
Paint quantity comes down to surface area, number of coats and the coverage printed on the can. Here is the method, with a full worked example.
How Much to Save Each Month to Reach a Savings Goal
Pick a target, a deadline and an expected interest rate, and a short formula gives the monthly deposit. A 20,000 goal in five years is the worked example.