· 4 min read
What Generation Am I? Birth-Year Cutoffs Explained
Boomer, Gen X, Millennial, Gen Z or Alpha? Learn the commonly used birth-year ranges, why the boundaries are fuzzy, and how to place yourself if you were born near a cutoff.
Articles by Lena Hoffmann
Science & education writer · View profile
· 3 min read
How to Convert a Percentage to a Fraction: Over 100, Then Reduce
A percentage is just a fraction out of 100. Put the number over 100, reduce to lowest terms, and handle decimal percentages like 12.5% by clearing the decimal first. With examples.
· 4 min read
What Is Kinetic Energy? The KE = ½mv² Formula Explained
Kinetic energy is the energy of motion, given by KE = ½mv². Learn what the formula means, why speed matters most, and see worked examples in joules.
· 4 min read
How Many Working Days Are There in a Year?
A year has roughly 260 weekdays before holidays. Learn where that number comes from, why it varies by country, and how public holidays bring it down to the working days you actually get.
· 4 min read
How to Add and Subtract Time (Hours and Minutes)
Add and subtract hours and minutes reliably. Learn to carry over 60, borrow when subtracting, and handle a result that crosses midnight into the next day.
· 4 min read
What Is Ohm's Law? V = I × R Explained Simply
Ohm's law links voltage, current, and resistance with one equation: V = I × R. Learn the triangle trick and see worked examples.
· 3 min read
How to Multiply and Divide Fractions: Multiply Across, Flip to Divide
Multiplying fractions needs no common denominator — just multiply across. Dividing means multiplying by the reciprocal. Learn both with worked examples and how to simplify.
· 3 min read
How to Add and Subtract Fractions: Common Denominator, Combine, Simplify
You can only add or subtract fractions that share a denominator. Learn to find a common denominator, combine the numerators, and simplify the result, with a worked example.
· 2 min read
Mean, Median and Mode: What's the Difference?
Mean, median and mode all describe the 'middle' of your data — but answer different questions. Here's what each means, with examples and when to use which.
· 4 min read
What Day of the Week Was I Born? Find Out in Seconds
Find the weekday of any birth date. Learn the quick calculator method and a short introduction to the Doomsday rule for working it out in your head.
· 4 min read
How Many Weeks Until a Date? (With Worked Examples)
Count the weeks between today and any future date. Learn the simple divide-by-seven method, when to round, and the difference between inclusive and exclusive counting.
· 4 min read
How to Do Long Division: Divide, Multiply, Subtract, Bring Down
Long division breaks a big division into a repeating four-step cycle. Learn the divide-multiply-subtract-bring-down loop and how to read the remainder, with a worked example.
· 3 min read
Order of Operations (PEMDAS / BODMAS): Why the Order Matters
PEMDAS and BODMAS are two names for one rule that fixes the order you evaluate a math expression — so everyone gets the same answer. Learn the rule with a worked example.
· 2 min read
Ordinal Numbers Explained: 1st, 2nd, 3rd
Ordinal numbers show position, cardinal numbers show quantity. Learn the difference and how each language forms ordinals differently.
· 3 min read
Percentage Change: Increase and Decrease
Subtract old from new, divide by the old value, times 100. Here's the formula, why increases and decreases aren't symmetric, and where it's used.
· 3 min read
How to Calculate Your Age
Subtract your birth year from this year, then take one off if your birthday hasn't come yet. Here's the rule, the common mistake, and how to get an exact age.
· 3 min read
Geometric vs Arithmetic Mean: Which to Use
The arithmetic mean adds and divides; the geometric mean multiplies and takes a root. Learn which fits growth rates, ratios, and averages.
· 3 min read
How to Calculate Standard Deviation (Step by Step)
Standard deviation measures how spread out your data is. Here's the formula, a worked example, and the difference between population and sample.
· 3 min read
How to Calculate Your GPA
GPA is a weighted average of your grades. Here's how to convert letter grades to points, weight by credits, and work out your overall GPA.
· 2 min read
Celsius to Fahrenheit: The Formula
Multiply by 9/5 and add 32. Here's the formula, the reverse, a quick mental shortcut, and the reference points worth committing to memory.
· 3 min read
How Many Days Between Two Dates
Subtract the earlier date from the later, minding month lengths and leap years. Here's how to count it, and whether to include both endpoints.
· 2 min read
kg to lbs: Formula and Quick Table
Multiply kilograms by 2.2046 for pounds. Here's the exact factor, how to go back, a quick mental estimate, and a reference table.
· 2 min read
cm to Inches and Feet
Divide centimetres by 2.54 for inches, or 30.48 for feet. Here's the formula, how to write a height in feet and inches, and a reference table.
· 2 min read
Roman Numerals Explained
Seven letters, added or subtracted. Here's what each stands for, how the subtractive pairs work, how to write any number, and where they still appear.