15×15=225=1×2× 100+25
25×25=625=2×3× 100+25
35×35=1225=××100+25
45×45==××100+25
4.5+15.5=
6-2.8=
12.5×4=
2.5×6=
1.9×5=
26.7+5.8=
8.2-7.7=
1.4×4=