import Control.Applicative ((<$>))
import Control.Monad (replicateM)
import Data.ByteString.Char8 (ByteString)
import Data.Char (isSpace)
import Data.List (unfoldr, foldl')
import qualified Data.ByteString.Char8 as B

getIntList :: IO [Integer]
getIntList = unfoldr f <$> B.getLine
    where
        f s = do
            (n, s') <- B.readInteger s
            return (n, B.dropWhile isSpace s')

evalSittable :: [Integer] -> Integer
evalSittable [c, d]
    | odd c     = ((c `div` 2) + 1) * d
    | otherwise = (c `div` 2) * d
    
solve :: [[Integer]] -> Integer
solve xss = (foldl' (\acc -> \xs -> acc + evalSittable xs) 0 xss) `mod` 1000000007

main :: IO ()
main = do
    n <- readLn :: IO Int
    solve <$> replicateM n getIntList >>= print