An electrical shop owner wants to purchase forty grinders and sixty ceiling fans from a retailer. If the cost of a grinder and that of a ceiling fan were Rs 2,750 and Rs 1,500 respectively, then how many notes of Rs 500 should he give to the retailer in order to buy the items? 

Cost of one grinder = Rs 2,750 

∴ Cost of 40 grinders = 40 × Rs 2,750 = Rs 1,10,000 

Cost of one ceiling fan = Rs 1,500 

∴ Cost of 60 ceiling fans = 60 × Rs 1,500 = Rs 90,000 

Therefore, the total amount of money needed to purchase 40 grinders and 60 ceiling fans 

= Rs 1,10,000 + Rs 90,000 = Rs 2,00,000 

Thus, the number of notes of Rs 500 that he should give to the retailer in order to buy the items is 2,00,000 ÷ 500 = 400