Q1.
Where else can we see such ‘non-decimals’ with a decimal-like notation?
Answer
Wherever a unit is not divided into 10 equal parts, a number written with a point is not a true decimal.
| Where you see it | What it looks like | What it really means |
|---|---|---|
| Cricket overs | 5.5 overs | 5 overs and 5 balls = 5 5⁄6 overs (1 over = 6 balls) |
| Clock time | 4.30 | 4 hours 30 minutes = 4 1⁄2 hours (1 hour = 60 minutes) |
| Feet and inches | 2.5 ft written for 2 ft 5 in | wrong! 2.5 ft is actually 2 ft 6 in (1 ft = 12 inches) |
| Cooking / recipes | 1.30 hours of baking | usually meant as 1 hour 30 minutes, not 1.3 hours |
| Version numbers | Class notes version 2.10 | the tenth revision after 2, not "two point one" |
| Bus / train timings | Departure 18.45 | 18 hours 45 minutes |
Why it happens: a decimal point is only meaningful when the whole is split into 10, then 100, then 1000. Hours are split into 60, overs into 6 and feet into 12, so their "points" are just separators between two different units.
Tip: "The bus will reach 4.5 hours post noon" means 4 hours and 5⁄10 of an hour. One-tenth of an hour is 6 minutes, so 5 tenths is 30 minutes — the bus arrives at 4:30 p.m., not 4:05 or 4:50.