①61.27-8.13-1.87
②3.9+4.08+1.1+5.92
③255×105-255×5
④101×77
⑤25×43×4
⑥4200÷25÷4
①143+236+157
②28+136+264+172
③248-123-27
④167+49+33+151
⑤369-89-111
⑥486-76-24-186