`Bài 1`
`7715 : 308 = 25 (dư 15)`
`7715 | 308 `
`1555 | 25`
`15 |`
`Bài 2`
`A) 2009 × 867 + 2009 × 133`
`= 2009 × (867 + 133)`
`= 2009 × 1000`
`= 2 009 000`
`B) 2008 × 867 + 2009 × 133`
`= 2008 × 867 + 2008 × 133 + 133`
`= 2008 × (867 + 133) + 133`
`= 2008 × 1000 + 133`
`= 2 008 000 + 133`
`= 2 008 133`