Practical guides, how-tos and comparisons to get the most out of our free online tools.
6,000 of annual cash flow on 50,000 invested is 12 %. The same property bought outright yields 6 % on 250,000 — the doubling is the mortgage, and it is not in the ratio.
Camille Laurent · 3 min read
EBIT of 500,000 against interest of 50,000 is a cover of 10×. Refinance at a rate 3.6 times higher and the same business covers 2.78× — and neither figure has looked at the principal.
Camille Laurent · 3 min read
Net income of 50,000 on equity of 250,000 is an ROE of 20 %. The same profit on 500,000 of equity is 10 % — the extra ten points came from the debt, not from the business.
Camille Laurent · 3 min read
150,000 of net operating income against 120,000 of debt service is a coverage of 1.25 — the usual threshold. It also means a 20 % fall in income wipes the cover out entirely.
Camille Laurent · 3 min read
Power lost as heat is current squared times resistance. Ten metres of 1.5 mm² extension lead has 0.233 Ω there and back: 23.3 W at 10 A, and 59.7 W at 16 A.
Daniel Okonkwo · 3 min read
5,000 mAh drawn at 500 mA with 85 % efficiency runs for 8.5 hours instead of the arithmetic's 10. The same 15 % explains why a 5,000 mAh bank barely fills a 4,000 mAh phone once.
Daniel Okonkwo · 3 min read
A 20 m² living room at 200 lux needs 4,000 lumens, or five 800-lumen bulbs. Apply a kitchen worktop's 500 lux to the same floor and it asks for thirteen — which is the moment to stop lighting rooms and start lighting tasks.
Marco Bianchi · 3 min read
Ten 60 W bulbs on five hours a day cost 219 a year; the same ten in 9 W LED cost 32.85, a saving of 186.15. Cut the hours to one and the saving falls to 37.23 — the hours matter more than the wattage.
Marco Bianchi · 3 min read
In France only two of the six holiday periods differ between zones — and those two are two weeks apart from end to end. In Germany the summer break start spans thirty-five days between Länder. Neither can be computed: they are decreed, and a stale copy is the real hazard.
Antonio Delgado · 5 min read
For 2, 4, 4, 4, 5, 5, 7, 9 the coefficient of variation is 42.76 %. It is the right tool for comparing spread across different scales — and completely wrong for any scale whose zero was chosen by convention.
Lena Hoffmann · 3 min read
Five points give r = 0.853, which sounds strong. The threshold for significance at five points is 0.878, so this one falls short — and a perfect parabola scores exactly zero.
Lena Hoffmann · 3 min read
For 10, 12, 15, 11, 13, 14 the standard deviation is 1.87 and the standard error is 0.76. They answer different questions, and only one of them gets smaller as you collect more data.
Lena Hoffmann · 3 min read