①
②6×100+4×10000
③
④
①402×65=
②952×74=
③350×1700=
④389÷41=
⑤864÷47=
⑥637÷21=
50×20=
540÷90=
110×70=
750÷30=
240×50=
3600÷60=
701×49≈
361÷59≈