My goal is to generate random numbers that all have decimal precision errors.

Here are some examples of types of numbers I would like to generate:

1.8181818723678589 1.2727272510528564 0.444444477558136

Here are strategies I have tried.

`parseFloat("4.01500000000000000001");`

`BigDecimal.valueOf(ThreadLocalRandom.current().nextFloat()).multiply(BigDecimal.valueOf(ThreadLocalRandom.current().nextFloat())).doubleValue();`

None of the things I tried have created even a single number similar to that which I am looking for.

## Answer

Assuming that the exact values actually *meant* are:

- 1.81 repeating
- 1.27 repeating
- 0.4 repeating

Observe that in each number there are around 7 or 8 digits that are “correct”, and around 18 digits in total. `float`

s are usually precise to 7 to 8 digits, and `double`

s are usually precise to around 18 digits, so I suspect that these numbers are actually `floats`

(or 32-bit floating point numbers) that got “widened” to be `double`

s

1.81 repeating is 20/11, so I tried:

float i = 20f/11f; double d = i; System.out.println(d);

This prints exactly the value you saw – 1.8181818723678589.

1.27 repeating is 14/11 and 0.4 repeating is 4/9. You can try both of these yourself. They all produce your desired numbers. This strongly suggests that the errors are produced by widening a `float`

to 64 bits.