You have to use FatRat instead of Rat. 
> my Rat $x = 0.9 ** 20;
Type check failed in assignment to $x; expected Rat but got Num (0.121
+576654590569e0)
> my FatRat $y = FatRat(0.9) ** 20;
0.12157665459056928801

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In reply to Re: perl6 rational number problem by Anonymous Monk
in thread perl6 rational number problem by freakcoco

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