Question

What is smaller than a second?

Answer 1

Hint: Second is considered as a mean solar day or fraction of one second from total number of seconds in a day. It can be measure in different order of magnitude with the difference of order of 10 more or less from the previous which will discussed in below sections:

Complete answer:
A Decisecond or one tenth of a second can be considered as smaller than second, in different forms many people prefer to use seconds or Centiseconds(one hundredth of a second).
In most of the calculations or standard calculations or measurements we always use milliseconds (one thousandth of second) for example 150 milliseconds would be preferable over 1.5 deciseconds.
In the SI System of units only seconds, milliseconds, microseconds, nanoseconds or picoseconds are used, rest are the general units which can be used according to users' needs.
If seconds is a measurement of time we can use different references to calculate another measurement for example- blink of an eye or time taken by horse in one step. They can be used as a basic unit and can form a large unit according to users' needs during the measurement.

Note:
The decimal (base 10) system is most widely used in the world, which can be used in different types of measurement. But the time in its large format is divided into sexadecimal(base 60) or we can say 60 seconds or 60 mins. But overall it’s based on one complete rotation of earth, and the 1/86400th fraction of which is considered as a unit of time known as seconds.