4.47. Append three digits to $523 \ldots$ so that the resulting six-digit number is divisible by 7, 8, and 9.
4.47. Answer: 523152 or 523656.

The obtained number must be divisible by $7 \cdot 8 \cdot 9=504$. Dividing 523000 by 504 with a remainder: $523000=1037 \cdot 504+352$. Since $504-352=152$, the numbers 523152 and $523152+504=$ $=523656$ are divisible by 504. There are no other numbers divisible by 504 among the numbers from 523000 to 523999.