1;11+11=4
12+12=9
Vậy:13+13=14
vì (1+1).(1+1)=4
(1+2).(1+2)=9
=>(1+3).(1+3)=16
2;11.11=4
22.22=16
33.33=36
vì (1+1).(1+1)=4
(2+2).(2+2)=16
=>(3+3).(3+3)=36
("." Là dấu nhân)
3;2=6
3=12
4=20
5=30
6=42
9=90
vì 2.3=6
3.4=12
4.5=20
5.6=30
6.7=42
=> 9.10=90