令m=10a1+8
则10^n=79(10a1+8)+8
=790a1+79×8+8
=790a1+640
=10(79a1+64)
10^(n-1)=79a1+64
令a1=10a2+4
则10^(n-1)=79(10a2+4)+64
=790a2+79×4+64
=790a2+380
=10(79a2+38)
10^(n-2)=79a2+38
令a2=10a3+8
则10^(n-2)=79(10a3+8)+38
=790a3+79×8+38
=790a3+670
=10(79a3+67)
10^(n-3)=79a2+67
令a3=10a4+7
则10^(n-3)=79(10a4+7)+67
=790a4+79×7+67
=790a4+620
=10(79a4+62)
10^(n-4)=79a4+62
令a4=10a5+2
则10^(n-4)=79(10a5+2)+62
=790a5+79×2+62
=790a5+220
=10(79a5+22)
10^(n-5)=79a5+22
令a5=10a6+2
则10^(n-5)=79(10a6+2)+22
=790a6+79×2+22
=790a6+180
=10(79a6+18)
10^(n-6)=79a6+18
令a6=10a7+8
则10^(n-6)=79(10a7+8)+18
=790a7+79×8+18
=790a7+650
=10(79a7+65)
10^(n-7)=79a7+65
令a7=10a8+5
则10^(n-7)=79(10a8+5)+65
=790a8+79×5+65
=790a8+460
=10(79a8+46)
10^(n-8)=79a8+46
令a8=10a9+6
则10^(n-8)=79(10a9+6)+46
=790a9+79×6+46
=790a9+520
=10(79a9+52)
10^(n-9)=79a9+52
令a9=10a10+2
则10^(n-9)=79(10a10+2)+52
=790a10+79×2+52
=790a10+210
=10(79a10+21)
10^(n-10)=79a10+21
当a10=1时
10^(n-10)=79+21=100=10^2
即：n-10=2
n=12
m=(10^12-8)÷79=12658227848