Final answer:
The number known as diamond jubilee, which is greater than 50 and smaller than 100, is 75.
Step-by-step explanation:
The number you are referring to, which is greater than 50 and smaller than 100 and known as diamond jubilee, is 75. The term 'diamond jubilee' is often used to mark the 75th anniversary of a significant event, such as a monarch's reign or the founding of an organization, and hence the number 75 is associated with the term. The number 75 lies within the range specified, meeting both the criteria of being greater than 50 and less than 100.