1. A computer-implemented method, comprising: receiving, in a computing system, data associated with a multi-dimensional cube, wherein the multi-dimensional cube includes multiple cells, and wherein each of the cells is referenced by an index number; receiving a cell selection rule; identifying one or more cells within the multi-dimensional cube, wherein identifying is based on the received cell selection rule and is performed on a computing device, wherein each cell is associated with multiple dimensions in the multi-dimensional cube, wherein each dimension includes a plurality of dimension members, and wherein each dimension member is associated with one or more offset values; determining that the identified cells form a sub-cube within the multi-dimensional cube, wherein determining includes finding that two of the identified cells share same dimension members from all but one dimension of the multi-dimensional cube; calculating, with one or more computer processors, the index number that references a start cell in the sub-cube, wherein calculating the index number that references the start cell includes using offset values associated with dimension members associated with the start cell; calculating, with the one or more computing processors, the index numbers that reference each other cell in the sub-cube, wherein calculating the index numbers includes using the index number that references the start cell and involves: 
 calculating flatIndex2=flatIndex1+dimMultipliers[dim]×(rank2−rank1), wherein: flatIndex2 represents a cell index of a cell to be identified, flatIndex1 represents a known cell index of a base cell, rank1 represents an offset value of a dimension member of the base cell, rank2 represents an offset value of a dimension member of the cell to be identified that is in a same dimension as the dimension member of the base cell, dim represents the dimensions of the multi-dimensional cube; and dimMultipliers[dim] represent multipliers of the dimensions of the multi-dimensional cube; and outputting the cell index numbers for the sub-cube, wherein the outputted cell index numbers identify the cells in the sub-cube.