India needs Rs. 200/- currency notes
India needs a Rs . 200/- note, not a Rs . 2,000/- note and the science behind it says Ravi Abhyankar: What should be the size of the Apple Mac screen? Technically , Apple can produce hundreds of different sizes, but they have settled on four: - 13.3 inch, 15.4 inch, 21.5 inch and 27 inch. The four are spaced close enough and far enough to satisfy most Apple consumers. Industrial design has a mathematical concept called preferred numbers. Way back in 1870s, a French engineer Charles Renard proposed a system based on logarithmic scale to produce a limited number of sizes to cover a wide range. A variant of that internationally accepted system is the 1-2-5 series, which is widely used in minting coins and printing notes. The 1, 2, 5, 10, 20, 50, 100, 200, 500, 1000… is that series. The beauty of the series is that any adjacent numbers differs by a product of 2 or 2.5. As a result, they are spaced close enough but cover a wide ground. How? Let us