It is hard to determine a person that has a number tied to their name, unless you know what the numbers stand for. The numbers 123456789 could be an id number for someone in the government or a persons id number in witness protection.
123456789 + 123456789 = 246913578
the answer is 15241578750190521
15,241,578,750,190,521
you get cheese
543234567890-123456789 = 543111111101
1
324536
123456789 + 36853168 = 160309957
123456789 +987654321 =1111111110
123456789 X 123456789 is1.52415788 × 1016
123456789-987654321 = -864197532
100000000-123456789 = -23456789