A terminating decimal ends after a certain finite number of decinal places, and does not have to be rounded off. An example would be 378 = 0.875

Your selfterminating decimal fractions are: 2/5, 1/25, and 7/8

So how would I form a conjecture of the terminating decimals?

Try to factorize the denominators of all those examples and see if you can come up with a conjecture.

Also, have you done rational and irrational numbers?

More examples of other self-terminating decimals for your conjecture:

1/16 = 0.0625
4/250 = 0.016
3/8 = 0.375
17/50 = 0.34
....

Yes, I figured out the rational and irrational numbers. I din't know what conjectures were or how they related.

Factorize the denominators, examine the factors and see if you would discover something.

To form a conjecture about terminating decimals, you need to analyze the common properties and characteristics of numbers that have finite decimal representations.

Here are the steps to create a conjecture about terminating decimals:

1. Start by examining some examples of terminating decimals. Look at different fractions and their corresponding decimal representations. For example, observe fractions like 2/5, 1/25, and 7/8, which you mentioned are terminating decimals.

2. In each example, identify the numerator and denominator of the fraction. For instance, in the fraction 2/5, the numerator is 2, and the denominator is 5.

3. Analyze the denominator of each fraction. Notice any patterns or characteristics that the denominators of terminating decimals exhibit. For instance, in the examples given, the denominators are 5, 25, and 8. You might observe that the denominators are relatively small numbers or have specific factors.

4. Consider the prime factorization of the numbers. This can help you determine if certain factors contribute to a fraction being a terminating decimal. Look for any common factors or prime numbers in the denominators of the examples you have explored.

By analyzing multiple examples and their corresponding decimal representations, you can make observations about the denominators of terminating decimals. These observations can lead to a conjecture or educated guess on the properties that indicate a fraction will have a terminating decimal representation.

For example, based on the examples you provided, you might make a conjecture that fractions with denominators that are powers of 5 (e.g., 5, 25, 125) will result in terminating decimals. However, it's important to test this conjecture with additional examples and further mathematical investigation to confirm its accuracy.