SageMath sometimes returns a very small number instead of 0
I am new to SageMath. Today I used it as a calculator and found the following:
In [1]: 14 * 1.2 - 16.8
Out [1]: 0.000000000000000
In [2]: 12 * 1.4 - 16.8
Out [2]: -3.55271367880050e-15
Why is it that for two very similar calculations it returns once 0 (which is correct) and then an approximate version of 0? How can I avoid this approximate result to receive a more precise answer? Did I do something wrong, meaning should I specify something extra?
Note: I wanted to include a screen capture of this calculus but since I am a new user I was not yet allowed to include pictures.
Text representation is better than screen capture, as it allows people to copy-paste.
Thank you all very much for your clear and helpful answers!