64=8*8
8*5=40

81=9*9
9*7=63

16=4*4
4*4=16

3^2+2^2+1^2=14
4^2+6^2+8^2=116
6^2+8^2+2^2=104

7^2+63^2+45^2=6043

5+6+1+4=16
16/2=8

7+6+2+9=24
24/3=8

Similarly,

13+11+5+19=48
48/6=8

8*3=24-3=21
6*5=30-5=25
12*2=24-2=22

5*3+6*8=63
2*7+3*9=41
6*7+8*5=82....

(48-24)=24 (2+4)-(4-3)=5 (72-19)=53 (5+3)-(8-3)=3 (60-12)=48 (4+8)-(9-5)=8.......