If you go to Reporting > Custom Report > New Report under display columns select the contacts you wish to see the NI numbers of e.g. contact 1 and then run the report. Once run you will have a column which shows the contact NI number.
If you go to Reporting > Custom Report > New Report under display columns select the contacts you wish to see the NI numbers of e.g. contact 1 and then run the report. Once run you will have a column which shows the contact NI number.