Articles

Leap years explained simply: a year is a leap year when it divides by 4, except century years, which must also divide by 400. See the rule and the reason.

Learn how to count the number of days between two dates by hand: add up full months, handle February and leap years, and pick inclusive or exclusive counting.

A year has 365 days, but you actually work only about 250 of them. See how 365 becomes 261 weekdays, then about 250 to 261 working days after holidays.

Business days vs calendar days explained simply: calendar days count every day, while business days count weekdays minus public holidays. See when each is used.

Learn how to calculate your exact age in whole years, then in years, months, and days, with a clear birthday check and a worked example you can follow.

Learn how to size a home backup battery or generator by adding up your watts, planning for surge watts, and using watt-hours to estimate runtime.

How many solar panels do you need? Size your array in three steps: find yearly kWh use, get system kW from peak sun hours, then divide by panel wattage.

Learn how to read your electricity bill, understand what a kWh is, and use the formula cost = kWh x rate to find and cut your home’s biggest power users.

Solar panel payback period explained: divide net system cost by annual savings. See the formula, a worked example, and what speeds up or slows the payback.

How to size an air conditioner using about 20 BTU per sq ft. See the room-size math, real-world adjustments, a BTU-to-tons chart, and when to call a pro.