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Inventories
9 Months Ended
Jan. 31, 2012
Inventories [Abstract]  
Inventories
2. Inventories

We use the last-in, first-out (“LIFO”) method to determine the cost of most of our inventories. If the LIFO method had not been used, inventories at current cost would have been $203.5 million higher than reported as of April 30, 2011, and $214.7 million higher than reported as of January 31, 2012. Changes in the LIFO valuation reserve for interim periods are based on a proportionate allocation of the estimated change for the entire fiscal year.