Practical guides, how-tos and comparisons to get the most out of our free online tools.
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.
Lena Hoffmann · 3 min read
Learn the three main commission models — flat percentage, tiered rates and base salary plus commission — with clear worked examples for each.
Camille Laurent · 3 min read
The debt-to-equity ratio measures leverage. Learn the formula, what a healthy level looks like, and how the personal version differs from the company one.
Camille Laurent · 3 min read
How much water you really need depends on your body weight, activity and climate — not a fixed "8 glasses". Here is how to estimate your daily target.
Sofia Nunes · 3 min read
A hashtag makes a post findable in a query, which is a different job from making it spread. Model the visibility a tag actually buys and the answer falls out: a tag's worth is its viewers-per-post-published, not its volume — so a very popular tag returns almost nothing and a specific one returns twenty-five times more.
Camille Laurent · 12 min read
JPG, PNG and WebP each win in different cases. Here is when to use each for the best balance of quality, file size and compatibility.
Daniel Okonkwo · 3 min read
A strike scores ten plus your next two balls, a spare ten plus your next one. That bonus chain is the entire game — it is why a perfect game is 300 and why alternating strikes and spares scores 200, not the 250 almost everyone guesses.
Aisha Karim · 11 min read
A practical guide to pricing: work out your unit cost, apply cost-plus pricing, understand markup versus margin, and know when to price on value instead.
Daniel Okonkwo · 4 min read
Running pace is time per kilometre or mile. Here's how to work it out from any run, convert between units, and use it to pace a race without blowing up.
Aisha Karim · 3 min read
ERA measures what happened, FIP measures only what the pitcher controls without his fielders, WHIP measures traffic allowed. Two pitchers can swap places entirely between them — and the gap between ERA and FIP is a forecast, not a verdict.
Aisha Karim · 10 min read
Estimate paint by wall area, coats and the coverage on the tin — with a worked example and the 10% rule so you buy once and match the colour.
Marco Bianchi · 2 min read
OPS adds two fractions with different denominators, which as arithmetic is indefensible. It survives because it tracks run scoring far better than batting average and costs nothing to compute — but it underpays on-base ability, and OPS+ does not fix that.
Aisha Karim · 10 min read