This is the reason why we are using inverted page table .
For 64 bit, we have 264 / 8kb = 251 single page table entries , so the size of page table will be for 4 bytes entry size is 253 . A very big page table to store per process .
Hence , we use inverted page table to store entry per physical frame which are 218 and take each entry to be 10 bytes suppose = 24
Then size of page table will be approx 2 MB.which is very less as compared to previous.
In case of inverted, entry size is upto 16 bytes and for simple paging it is upto 4 bytes.