900 x 900 = 9002 = 810000
Ta có:
2222/1818
=1111/909
=11/9
200 + 6 x 5
= 200 + 30
= 230.
5+5+5+6 = 21 5+5+5+5+2 =22
5+5+5+6=5x3+6=21
5+5+5+5+2=5x4+2=22
500 + 500 = 1000