`274 + (158 + 26)`
`=274 + 158 +26`
`=(274 + 26)+158`
`=300 + 158`
`=458`
_______________________________
`3.125.121.8`
`=(125.8).(3.121)`
`=1000 . 363`
`=363000`
____________________________________
`29 + 132 + 237 + 868 + 763`
`=(132 + 868) + (237 + 763) + 29`
`=1000 + 1000 + 29`
`=2000 + 29`
`=2029`
________________________
`25.5.4.31.2`
`=(25.4).(5.2).31`
`=100.10.31`
`=1000.31`
`=31000`
________________________
`98.31+62`
`=98.31+31.2`
`=31.(98+2)`
`=31.100`
`=3100`
a) \(274+\left(158+26\right)\)
\(=274+158+26\)
\(=158+\left(274+26\right)=158+300=458\)
c) \(3.125.121.8\)
\(=\left(125.8\right).\left(3.121\right)=1000.363=363000\)
e) \(29+132+237+868+763\)
\(=29+\left(132+868\right)+\left(237+763\right)\)
\(=29+1000+1000=2029\)
g) \(25.5.4.31.2\)
\(=\left(25.4\right).\left(5.2\right).31=100.10.31=31000\)
i) \(98.31+62\)
\(=98.31+31.2\) \(=31.\left(98+2\right)=31.100=3100\)