Guides, worked examples and how-tos for the calculators on CalcScholar: grades and CGPA, money and tax, health, maths and everyday numbers.
How to calculate tax on salary in Pakistan for FY 2026-27: the slabs, six worked monthly salaries, and why a raise costs less tax than it looks.
Aggregate vs merit list explained: the difference between a weighted admission aggregate and a closing merit list, why merit moves every year, and how to solve backwards for a target score.
How many classes can I miss? How a minimum attendance percentage actually works, why the same 75% rule gives every student a different safe margin, and a worked example showing exactly how many classes you can miss.
Marks to percentage conversion explained for one subject and for several subjects combined, with the formula, worked examples, reverse conversion and Excel formulas.
How to convert CGPA to percentage: why no single official formula works, how the linear, ×20 and published-table rules compare, and worked examples for 4.0, 5.0 and 10-point scales.
How to convert GPA to percentage: how a single semester's GPA converts under the linear rule, the ×20 rule of thumb and a published table, with worked examples on 4.0, 5.0 and 10-point scales and why the figure is noisier than a CGPA conversion.
How to convert percentage to CGPA: the linear, ×20 and published-table rules, why the top of the scale caps rather than overshoots, and worked examples for 4.0, 5.0 and 10-point scales.
The score needed on final exam day, worked out from your current grade and the exam's weight, with worked examples, a table of weights and what to do when the answer is above 100 or below zero.
How to build an unofficial transcript PDF: what belongs on the header, how SGPA rolls up into CGPA and percentage across terms, formats and templates, and how deficiency or repeat courses are handled.
How a weighted admission aggregate combines a prior academic record with an entrance exam into one number, with real-world examples, a full worked calculation and a checklist for Pakistani entry tests.
How to calculate a weighted grade: the formula, a step by step method, a worked example, and answers on weights that miss 100, extra credit, dropped scores and zeros.
Weighted average vs simple average: why the same numbers can give very different results, worked through with a credit-hour grade example, a portfolio return, Excel formulas and inventory cost.
How do I know if I'm ovulating? A hand-verified timing comparison of LH ovulation tests and basal body temperature charting, showing which one gives real advance notice and which only confirms ovulation days after it already happened.
A verified, side-by-side comparison of MDRD, CKD-EPI and the Mayo Quadratic formula across four patients, showing why the three give meaningfully different eGFR numbers for the same lab value, and why that gap shrinks as kidney function declines.
A worked comparison of all three major BMR formulas across a lean athlete, an average-body-fat adult, and a muscular heavier adult, showing exactly when the Katch-McArdle formula pulls furthest away from the other two, and why.
A step-by-step, worked-example walkthrough of the backdoor Roth IRA strategy for high earners above the income limit, including the pro-rata rule trap that catches people who skip it.
Types of gravel for driveway, path and drainage projects compared: bank gravel, crushed stone, pea gravel and river stone, with worked examples for a driveway base, a garden path and a French drain.
A hand-verified comparison of the Epley, Brzycki and Lombardi one rep max formulas, showing exactly where and why they agree, cross over, and pull apart at higher rep counts.
A worked look at direct versus indirect IRA rollovers, the 20% withholding trap on employer plans, the once-per-12-months limit, and exactly how the 60-day rollover rule works.
Karvonen vs age-based heart rate zones, worked through with two 40-year-olds who have different resting heart rates: why the two methods can disagree by double digits.
Pregnancy dating methods compared: how LMP, ultrasound, conception and IVF transfer dates each estimate a due date, why they disagree, and when a doctor redates.
Which is the most accurate body fat method? A real side-by-side worked example comparing the U.S. Navy tape method, Jackson & Pollock skinfold calipers, and the BMI-based Deurenberg formula for the same person.
A hand-verified 5K pacing comparison showing why negative splits and even pacing both beat starting too fast, using the same multipoint checkpoint math a splits calculator runs.
Percent off vs fixed amount off: the exact break-even price where a percent-off coupon and a fixed dollar-off coupon save the same amount, worked through with real numbers, plus a provable rule for which order to apply the two when they're stacked together.
Roth 401(k) vs traditional 401(k), compared dollar by dollar: when each one wins, and the hidden reason a Roth account can shelter more money under the same IRS limit.
BMI for athletes explained with worked numbers: why muscle raises BMI, what a 2025 DXA study of 622 athletes found, and how FFMI and waist-to-height ratio help.
Why so few babies are born on their due date: the statistics behind the 4 to 5 percent figure, why birth timing is skewed rather than symmetric, and how induction policy shapes the numbers.
Apple pear hourglass rectangle body shapes explained: what each one means, how common each is in a 6,000-woman body-scanning study, and what waist-to-hip ratio adds.
As the crow flies distance calculator math: how the haversine formula computes great-circle distance between two coordinates on Earth, worked through step by step with real city pairs and its accuracy limits.
What a certificate of deposit really is, how APY differs from APR, the CD ladder strategy explained with real numbers, and exactly what an early withdrawal penalty costs.
Extra mortgage payments and biweekly schedules both cut years off a loan, but not by the same amount. Real numbers on three extra-payment types and a biweekly plan, compared side by side on identical loans.
Gross pay vs net pay explained with full worked examples: federal tax, FICA, an optional state rate, and how a 401(k) or health insurance premium change what actually lands in your bank account.
The history of the Gregorian calendar: why Pope Gregory XIII's 1582 reform dropped 10 days from the calendar, the leap year math behind it, and why some countries waited 300 more years to switch.
Hourly to salary calculator guide: how to convert an hourly wage into every pay period, and why Unadjusted and Adjusted annual totals differ once real holidays and vacation days are counted.
How an amortization schedule works: why the first payment on a loan is mostly interest, how a 15-year and 30-year schedule really compare, and what happens when extra payments, refinancing or a variable rate break the simple model.
How binary numbers work, explained from place value up: converting between binary and decimal by hand, and fully worked binary addition, subtraction and multiplication with every carry and borrow shown.
How much concrete do I need? A worked-example guide to estimating concrete volume for a slab, a set of fence-post footings, a circular pad, a curb and gutter run, and a flight of stairs, with hand-checked math for each.
Why a 20% off coupon plus an extra 15% off doesn't add up to 35% off, worked through on a real $279 example, verified to the cent, plus the general rule for any number of stacked discounts.
How tall will I be as an adult? A full walkthrough of the mid-parental formula and a WHO growth-based full predictor, with a worked example.
How to add and subtract time durations by hand, plus a full guide to the Time Calculator's typed expression syntax, with worked examples and common mistakes.
How to calculate a square root by hand with two verified methods: the averaging (Babylonian) method with three full worked examples, and the classic long-division algorithm, digit by digit.
How to calculate hours worked for payroll: a full walkthrough of quarter-hour rounding, converting minutes to decimal hours, overtime thresholds and the mistakes that make a paycheck wrong.
Square footage of an odd shaped room: split the floor plan into rectangles, triangles and circle pieces, then add or subtract each area, with worked examples.
How to find the duration between two times by hand, including the borrow step when minutes run short, plus how the same idea extends to two full dates and times.
How to convert fractions to decimals and decimals back to fractions: a complete guide, including why some decimals repeat forever, the algebra trick for turning one back into an exact fraction, and a fraction-decimal-percent reference table.
How to do long division: a full worked long division example, digit by digit, covering both the remainder form and continuing the same working past the decimal point, every step verified by hand.
How to measure my foot size at home: the standing paper-and-wall method, the math that turns millimetres into sizes, real average foot sizes, and width.
The five core Roman numeral rules behind every correctly formatted numeral, verified against real examples like 1994 = MCMXCIV, plus the most common mistakes people make writing them.
How to solve a right triangle with the Pythagorean theorem and the three SOH-CAH-TOA trig ratios, with worked examples for several different combinations of known values.
Mean, variance, standard deviation explained in plain language with one shared data set, plus the five number summary and a dedicated section on geometric mean and when it beats a plain average.
Percentage difference vs percentage change explained: both formulas, worked comparisons across five pairs of numbers, and when each one, plus percent error, is the right tool.
A road trip cost calculator in four steps: turn a planned trip's miles into a real budget, with mileage reimbursement if it's for work, fuel cost from your vehicle's economy, and a drive-time estimate from distance and average speed.
How to build a factor tree by hand with a fully verified worked example, why every path through the tree lands on the same prime factors, and why factoring huge numbers is still genuinely hard even for computers.
Dice roll probability explained, from the 1-in-6 chance of any single face to the full 2d6 distribution and why 7 is the most common roll, verified by counting every combination by hand.
Simple vs compound interest: simple interest grows in a straight line, compound interest curves upward. Full derivations, worked tables across decades and compounding frequencies, the Rule of 72, and how tax quietly erodes compounding.
Trade-in value auto loan math explained: trade-in value and trade-in equity are not the same number. A full walkthrough of how positive equity, negative equity, sales tax and GAP insurance each change what you actually finance.
True random vs pseudo random numbers: what separates them, why Math.random() is not cryptographically secure, and what a uniform distribution actually means.
CST to EST is one hour forward, but the abbreviation you pick decides whether that is right. Full conversion charts for Central, Eastern, Mountain and Pacific, plus UTC and GMT.
How to calculate CGPA in Pakistan step by step: the HEC-style grading scale, quality points, the SGPA and CGPA formulas, and a fully worked semester example.
The SGPA vs CGPA difference explained with a real five-semester Pakistani transcript, what counts as a good CGPA, and how many credit hours move one.