Determine the unused node numbers and reassign sequential node numbers.
From the Main Menu select Node/Element > Nodes > Compact Node Numbers.
Click to the right of Compact Node Numbers: Display Node Table
Define Starting Node number by clicking . Refer Start Number
Assign the range of node numbers to compact.
All: All the nodes are targeted
By Number: A particular range of node numbers is targeted
Starting Number: Starting node number of the range
Ending Number: Ending node number of the range