Bài 1:
1: \(176+228+272+324\)
=176+324+228+272
=500+500
=1000
2: \(526-131-326+321\)
=526-326+321-131
=200+190
=390
3: \(545\cdot65+15\cdot545-80\cdot445\)
\(=545\left(65+15\right)-80\cdot445\)
\(=80\left(545-445\right)=80\cdot100=8000\)
4: \(31\cdot175-31\cdot50+69\cdot125\)
\(=31\cdot\left(175-50\right)+69\cdot125\)
\(=125\cdot31+125\cdot69=125\cdot\left(31+69\right)=125\cdot100=12500\)
5: \(43\cdot78-43\cdot48+30\cdot80-30\cdot23\)
\(=43\cdot\left(78-48\right)+30\cdot\left(80-23\right)\)
\(=43\cdot30+30\cdot57=30\cdot\left(43+57\right)=30\cdot100=3000\)
6: \(64\cdot57+64\cdot43-2300\)
\(=64\cdot\left(57+43\right)-2300\)
=6400-2300=4100
Bài 2:
1: \(3\cdot5^2-16:2^2=3\cdot25-16:4=75-4=71\)
2: \(200:\left[117-\left(23-2\cdot3\right)\right]\)
\(=\dfrac{200}{117-23+6}=\dfrac{200}{123-23}=\dfrac{200}{100}=2\)
3: \(2^3\cdot17-2^3\cdot14=2^3\left(17-14\right)=8\cdot3=24\)
4: \(2020-\left[45-\left(6-1\right)^2\right]+1992^0\)
\(=2020-\left[45-5^2\right]+1\)
\(=2020-20+1=2001\)
5: \(20-\left[30-\left(5-1\right)^2\right]\)
\(=20-\left[30-4^2\right]\)
\(=20-\left(30-16\right)=20-14=6\)
6: \(480:\left[75+\left(7^2-8\cdot3\right):5\right]+2021^0\)
\(=\dfrac{480}{75+\left(49-24\right):5}+1\)
\(=\dfrac{480}{75+\dfrac{25}{5}}+1=\dfrac{480}{80}+1=6+1=7\)
7: \(8\cdot5^2-189:3^2\)
\(=8\cdot25-189:9\)
=200-21=179
8: \(2^4\cdot5-\left[131-\left(13-4\right)^2\right]\)
\(=16\cdot5-\left[131-9^2\right]\)
\(=80-\left(131-81\right)=80-50=30\)
