The Set number building block is used to define a number value, typically to be used as a constant in other building blocks such as Calculate.
The Set number block has only one property:

The Block Header (“Set number”)
There are no green input or output connectors in the header, because this building block is never explicitly executed. Rather, it is used to set a number value and deliver it to other building blocks.
The title of the block (“Set number”) can be changed by double-clicking on it and typing in a new title.
Number value
The value of the number.
Updated June 8th 2016.