1.

Find the rational number whose decimal form is `0.bar(142)`.

Answer» We have
`0.bar(142).0.142424242...`
`=0.1+0.042+0.00042+0.0000042+...oo`
`=1/10+{42/10^(3)+42/10^(5)+42/10^(7)+...oo}`
`=1/10+((42/10^(3)))/((1-1/10^(2)))[("this being a GS in which "),(a=42/10^(3) and r=(42/10^(5)xx10^(3)/42)=1/10^(2) lt 1)]`
`=1/10+(42/1000xx100/99)=(1/10+42/990)=141/990`
Hence, `0.bar(142)=141/990`.


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