The statistical properties of the solar soft X-ray (SXR) flare fluence, i.e. the time integral of SXR flux of a flare, FSXR\documentclass[12pt]{minimal}
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\begin{document}$F_{\mathit{SXR}}$\end{document}, and sum of the FSXR\documentclass[12pt]{minimal}
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\begin{document}$F_{\mathit{SXR}}$\end{document} of all flares produced by a solar active region (AR), FAR\documentclass[12pt]{minimal}
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\begin{document}$F_{\mathit{AR}}$\end{document}, during 1997–2008 have been investigated. The results show that FSXR\documentclass[12pt]{minimal}
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\begin{document}$F_{\mathit{SXR}}$\end{document} has moderate correlation with the area of the associated AR, while the correlation between FAR\documentclass[12pt]{minimal}
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\begin{document}$F_{\mathit{AR}}$\end{document} and the largest area of the associated AR is also moderate. The total number of ARs that can produce at least one SXR flare during 1997–2008, Nt\documentclass[12pt]{minimal}
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\begin{document}$N_{t}$\end{document}, is 1408. The sum of FAR\documentclass[12pt]{minimal}
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\begin{document}$F_{\mathit{AR}}$\end{document} produced by 1408 ARs, ∑FAR\documentclass[12pt]{minimal}
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\begin{document}$\sum F_{\mathit{AR}}$\end{document}, is 89 585.81 (erg s cm−2) and the average value of FAR\documentclass[12pt]{minimal}
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\begin{document}$F_{\mathit{AR}}$\end{document} is 63.6 (erg s cm−2). 34 ARs (FAR≥500ergscm−2\documentclass[12pt]{minimal}
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\begin{document}$F_{\mathit{AR}}\ge 500\ \mbox{erg}\,\mbox{s}\,\mbox{cm}^{-2}$\end{document}) contributed 55.72 % of ∑FAR\documentclass[12pt]{minimal}
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\begin{document}$\sum F_{\mathit{AR}}$\end{document}. 111 ARs (100(ergscm−2)≤FAR<500(ergscm−2))\documentclass[12pt]{minimal}
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\begin{document}$(100\ (\mbox{erg}\,\mbox{s}\,\mbox{cm}^{-2})\le F_{\mathit{AR}}<500\ (\mbox{erg}\,\mbox{s}\,\mbox{cm}^{-2}))$\end{document} contributed 24.33 % of ∑FAR\documentclass[12pt]{minimal}
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\begin{document}$\sum F_{\mathit{AR}}$\end{document}. 437 ARs (10(ergscm−2)≤FAR<100(ergscm−2))\documentclass[12pt]{minimal}
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\begin{document}$(10\ (\mbox{erg}\,\mbox{s}\,\mbox{cm}^{-2} )\le F_{\mathit{AR}}< 100\ (\mbox{erg}\,\mbox{s}\,\mbox{cm}^{-2}))$\end{document} contributed 17.48 % of ∑FAR\documentclass[12pt]{minimal}
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\begin{document}$\sum F_{\mathit{AR}}$\end{document}. The rest 826 ARs only contributed 2.52 % of ∑FAR\documentclass[12pt]{minimal}
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\begin{document}$\sum F_{\mathit{AR}}$\end{document}. The number of ARs decreases dramatically with FAR\documentclass[12pt]{minimal}
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\begin{document}$F_{\mathit{AR}}$\end{document} and the distribution function of FAR\documentclass[12pt]{minimal}
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\begin{document}$F_{\mathit{AR}}$\end{document} is N(FAR)=2840e−0.1286FAR\documentclass[12pt]{minimal}
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\begin{document}$N(F_{\mathit{AR}})=2840e^{-0.1286F_{\mathit{AR}}}$\end{document}.
