1. A method of video decoding, performed by at least one processor, the method comprising: obtaining, from a bitstream, an x index indicating an x coordinate of a last significant coefficient, from among transformation coefficients of a transformation block, and a y index indicating a y coordinate of the last significant coefficient; determining a scan index of the last significant coefficient based on the x index and the y index; obtaining, from the bitstream, level information of the last significant coefficient; reconstructing the last significant coefficient using the level information of the last significant coefficient; obtaining, from the bitstream, a significant coefficient flag and level information of a first transformation coefficient which has a smaller scan index than the scan index of the last significant coefficient among the transformation coefficients; reconstructing the first transformation coefficient by using the significant coefficient flag and the level information of the first transformation coefficient; and performing inverse transformation on the transformation block using transformation coefficients including the last significant coefficient and the first transformation coefficient, wherein the significant coefficient flag indicates whether a level of the first transformation coefficient is zero or non-zero, and wherein the level information of the first transformation coefficient indicates the level of the first transformation coefficient is greater than 1, when the significant coefficient flag indicates the level of the first transformation coefficient is non-zero.