how to find table row number in angular 10 code example

Example: material table get index of row

<ng-container matColumnDef="position">
  <th mat-header-cell *matHeaderCellDef mat-sort-header> Num. </th>
  <td mat-cell *matCellDef="let element; let i = index">{{i + 1}}</td>
</ng-container>