Suppress each of the digits in 1729404 and add the resulting numbers, and you get 1729404 again:
729404 129404 179404 172404 172904 172944 + 172940 1729404
Another example:
3758846 1758846 1358846 1378846 1375846 1375846 1375886 + 1375884 13758846
Suppress each of the digits in 1729404 and add the resulting numbers, and you get 1729404 again:
729404 129404 179404 172404 172904 172944 + 172940 1729404
Another example:
3758846 1758846 1358846 1378846 1375846 1375846 1375886 + 1375884 13758846