✍️ Knowledge Hub

APluscalc Blog

Deep dives into math, finance, science, and productivity. Learn the formulas behind your favourite calculators.

Compound interest — the 8th wonder of the world explained
Finance
The Magic of Compound Interest: Why Einstein Called It the 8th Wonder
Discover why starting to invest even $100 a month in your 20s can make you a millionaire by retirement — the mathematics explained.
Dec 15, 2025 · 8 min read
Read Full Article →
History of scientific calculators
Math
Scientific Calculators: A History from Slide Rules to Silicon
From Napier's bones in 1617 to the HP-35 in 1972 to your smartphone — the fascinating 400-year history of calculation.
Dec 10, 2025 · 12 min read
Read Full Article →
Rent vs buy — complete financial analysis
Finance
Should You Rent or Buy? The Complete Financial Analysis
We break down the true cost of homeownership vs renting, using real mortgage math to help you make the biggest financial decision of your life.
Dec 5, 2025 · 15 min read
Read Full Article →
Space distances — how far is a light-year
Science
How Far Is a Light-Year? Making Space Distances Tangible
If you drove a car at highway speed to the nearest star, you'd arrive in 37 million years. We explore the mind-bending scale of the universe.
Nov 28, 2025 · 10 min read
Read Full Article →
BMI: useful tool or outdated science
Health
BMI: A Useful Tool or Outdated Science? The Complete Guide
BMI was invented in the 1830s and was never meant to measure individual health. We explore its uses, limitations, and better alternatives.
Nov 20, 2025 · 9 min read
Read Full Article →
The 8 glasses a day water myth
Health
The 8 Glasses a Day Myth: What Science Actually Says About Hydration
The "8x8" rule was never backed by science. Here's what research actually says about how much water your body needs each day.
Nov 15, 2025 · 7 min read
Read Full Article →
How foreign exchange rates are set
Finance
How Foreign Exchange Rates Are Set — And Why They Move
Central banks, interest rates, inflation, and geopolitics — the forces that determine why your currency is worth what it's worth today.
Nov 8, 2025 · 11 min read
Read Full Article →
GPA explained: how to calculate it
Education
GPA Explained: How to Calculate It and Why It Matters
From letter grades to the 4.0 scale — we explain weighted GPA, how graduate schools evaluate it, and strategies to improve yours.
Nov 1, 2025 · 8 min read
Read Full Article →
Time zones — why the world has 38 of them
Productivity
Time Zones: Why the World Has 38 of Them, Not 24
Half-hour offsets, daylight saving chaos, and India's unusual GMT+5:30 — the surprisingly political history of global time.
Oct 25, 2025 · 9 min read
Read Full Article →
Calorie counting — what science says
Health
Do You Really Need to Count Calories? The Science of Weight Loss
Calorie counting works — but it's just one tool. We explore TDEE, BMR, and the most evidence-based approaches to sustainable weight management.
Oct 18, 2025 · 10 min read
Read Full Article →
EMI explained: loan repayment made simple
Finance
Understanding EMI: How Your Loan Repayment Actually Works
Why do early loan payments mostly pay interest? We explain amortization, EMI calculation, and how to save thousands with extra payments.
Oct 10, 2025 · 8 min read
Read Full Article →
Metric vs imperial: why the US has not switched
Science
Metric vs Imperial: Why the US Hasn't Switched and What It Costs
Three countries still use imperial units. The Mars Climate Orbiter was destroyed because of this. We explore the $100 billion measurement divide.
Oct 3, 2025 · 11 min read
Read Full Article →
BMI 34 before surgery: reduce your risk
Health
BMI 34 Before Surgery: Everything You Must Do to Reduce Your Risk
A BMI of 34 raises real surgical risks. With the right 8–12 week preparation — diet, exercise, blood sugar control — you can significantly improve your safety and healing.
May 11, 2026 · 10 min read
Read Full Article →

❓ Frequently Asked Questions

What topics does the APluscalc blog cover?

The blog covers math, finance, health, and science topics — explaining how calculators work, the history behind formulas, and practical guides for everyday calculations like BMI, compound interest, mortgage payments, and calorie counting.

How often is new content published?

New articles are published regularly, covering in-depth financial guides, health science explainers, and topics that make complex calculations and formulas easy to understand for everyday readers.

Are the articles free to read?

Yes. Every article on the APluscalc blog is completely free — no signup, no subscription, no paywall. The blog is supported by the same free calculator tools available across the site.

Can I use the calculators mentioned in articles?

Yes. Each article links directly to the relevant free calculator. The BMI guide links to the BMI Calculator, the compound interest article links to the Compound Interest Calculator, and so on — so you can apply what you read immediately.

How accurate is the information?

APluscalc articles are based on established scientific and financial sources including WHO guidelines, IRS tax brackets, and peer-reviewed research. All formulas are verified against industry-standard methods.