Decimals
A decimal number is any number with a nonzero digit to
the right of the decimal point. But for the SAT, it’s more important
to know that decimals are, like fractions, a way of writing parts
of wholes. If you have to add, subtract, multiply, divide, or perform
any other operation on a decimal for the SAT, we highly recommend
that you use a calculator. It will save more time and you will make
fewer mistakes.
Converting Decimals to Fractions
Even if you use a calculator, you should know how to convert
decimals into fractions and vice versa. Both conversions are easy
to do.
To convert a decimal number to a fraction,
-
Remove the decimal point and make the decimal number
the numerator.
- Let
the denominator be the number 1 followed by as many zeros as there
are decimal places in the decimal number.
- Reduce
this fraction.
To convert .3875 into a fraction, first eliminate the
decimal point and place 3875 as the numerator:
Since .3875 has four digits after the decimal
point, put four zeros in the denominator following the number 1:
Then, by finding the GCF of 3875 and 10,000, which is
125, reduce the fraction:
To convert from fractions back to decimals is a cinch:
divide the numerator by the denominator on your calculator:
