Magento: Convert price from default currency to some other currency

To convert the price to some other currency we need to select that currency in allowed currency and import currency rates from System->Manage currency ->Rates .
The synatx for currency conversion is currencyConvert($amount, $from, $to=null)
e.g:
Suppose we need convert Price from GBP(British Sterling Pound) to INR(Indian currency) then we need to write below code .

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$convertedPrice = Mage::helper('directory')->currencyConvert($price, GBP, INR);
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