Rucete ✏ Mathematics In a Nutshell
How to round off
Rounding off a number is a mathematical term that refers to the process of converting a precise value to a less precise value.
Decimal places (dp)
Following the decimal places, count the values
0.246
2 and 4 are the first two digits following the decimal point.
The next value is 6, which is greater than 5, so round up by adding one to the preceding number, — in other words 4 in the second decimal place.
(1) π = 3.141592 = 3.1416 (to 4 dp)
(2) 124.345 = 124.34 (to 2 dp)
(3) 0.00823 = 0.008 (to 3 dp)
Significant figures (sf)
Count the numbers that begin with a non-zero digit
If the number does not contain a decimal point, the rightmost zeros serve as place holders.
Additionally, if the number contains a decimal point, begin counting from the first non-zero digit and count all significant digits to the right.
(1) π = 3.141592 = 3.142 (to 4 sf)
(2) 3.491 = 3.5 (to 2 sf)
(3) 0.00823 = 0.0082 (to 2 sf)
(4) 37268 = 37000 (to 2 sf)