Converting Decimal -0.21 to Fraction for 18-Year-Old Students

To convert the decimal -0.21 into a fraction, follow these steps:

1. Understand the decimal: The decimal -0.21 can be read as 'negative twenty-one hundredths'. This means we need to express the number 0.21 as a fraction first and then consider the negative sign.
2. Write the decimal as a fraction: The decimal 0.21 can be written as:

0.21 = 21/100

3. Add the negative sign: Since our original decimal is -0.21, we will include the negative sign in front of our fraction. Thus:

-0.21 = -21/100

4. Final answer: The fraction for -0.21 is:

-21/100

In conclusion, -0.21 can be expressed as the fraction -21/100.