During the majority of the 1970s, Sinclair focused on building the most affordable pocket calculators with the best design. In 1972 Sinclair released the world's first slim-line pocket calculator, the Sinclair Executive, for £79.95. The calculator only included basic maths functions, and the LED display required much power. It is often credited as being the world's first attractively styled calculator that did not require mains power to be used like prior calculators. The Executive was a phenomenal success, earning Sinclair £1.8m in profit. In 1973 the slightly larger Sinclair Cambridge was introduced at a far cheaper price of £29.95 + VAT. A cheaper Executive was also launched shortly after. In addition to expanding the Cambridge range, the Sinclair Scientific was launched in 1975. It was a scientific pocket calculator for the very competitive price of £49.95. In 1977 a revised model, the "Scientific Programmable", was released at £29.95. The Scientific Programmable Mark 2 was later released, reducing the price to £17.22.