Tính nhẩm:
6000 + 3000 – 5000
= 9000 - 5000
= 4000
8000 – 3000 – 2000
= 5000 - 2000
= 3000
7000 – (1500 + 4500)
= 7000 - 6000
= 1000
6000 + 2000 – 3000
= 8000 - 3000
= 5000
`6000 + 3000 – 5000= 9000-5000= 4000`
`8000 – 3000 – 2000=5000-2000=3000`
`7000 – (1500 + 4500)=7000-6000=1000`
`6000 + 2000 – 3000=8000-3000=5000`