A great article by HistoryExtra , on the Hindu-Arabic numeral system and mathematics which originated in India, and its evolution down the centuries. Digital revolution: the evolution of Hindu-Arabic numerals (HistoryExtra is the official website for BBC History Magazine and BBC History Revealed. )
Article on ancient India's impact on the world with mathematics. Five ways ancient India changed the world – with maths
The biggest problem with metric in engineering, is that 10 cannot be divided by 3 without a recurring decimal. I do all my designs in imperial, I still love the slide-rule. LOL