Decimal places allow you to specify how many decimals you wish to round a continuous qualitative variable to. As a standard, you will round to the nearest decimal place, either up or down, although Excel has a variety of rounding functions you can use including fixed round-ups and round-downs.
Example: 2.46874 to 3 decimal places would be 2.469.
Fractions simplest form
Fractions can be converted to their simplest form by reducing both the top and bottom figures to the lowest possible whole numbers. To do this you need to find the greatest common factor of the two numbers involved.
You can specify a number to a specific amount of significant figures to ensure you are reaching your required degree of accuracy. Unlike decimal places, this will include whole numbers before the decimal.
Example: 2.46874 to 3 significant figures would be 2.47, or to two significant figures it would simply be 2.5.
There is no set formula in Excel for setting significant figures but it can be achieved using a combination of the ROUND, INT, LOG10 and ABS functions.