Assuming it is the "456" that is repeating, writing x= 0.456456..., you can multiply by 1000 to get 1000x= 456.456456.... Notice that the two numbers have the same decimal part- because it is repeating that "456" just keeps coming. So if we subtract we get 100x- x= 99x= 456 and so \(\displaystyle x= \frac{456}{999}= \frac{152}{333}\).
