His second book, "Humble Pi," was released in March 2019 and was a Sunday Times #1 bestseller. In 2014, Parker set up Think Maths, a team of experienced mathematics speakers who visit schools to run workshops and give talks for a wide range of ages and abilities, to show students the wider world of maths beyond school while giving them a chance to develop mathematical thinking skills. Parker is a regular on BBC Radio Four's "Infinite Monkey Cage" with Robin Ince and Brian Cox. He has also talked about maths-related topics on BBC News, Sky News, Channel4, CBBC, and occasionally writes for "The Guardian". On TV, Parker is a regular commentator on Discovery's "Outrageous Acts of Science". For the 2019 edition of the Royal Institution Christmas Lectures, televised on BBC Four, Parker assisted presenter Hannah Fry in several segments. In October 2017, Parker started a petition to "Update the UK Traffic Signs Regulations to a geometrically correct football." In a YouTube video, he explained why the current football shape on traffic signs is incorrect and geometrically impossible. Parker described the current signs as "national embarrassment" and said he hopes the petition will "help raise public awareness and appreciation of geometry." Parker discussed the issue on You Can't Polish A Nerd. According to him, the government initially dismissed the petition because he is a comedian. By November 2017, the petition had gained over 21,000 signatures. The UK government has responded saying "the current football symbol has a clear meaning and is understood by the public. Changing the design to show accurate geometry is not appropriate in this context." Parker said he felt "like the Department for Transport had not read the petition properly". The official response stated it would be too costly to replace the current signs; however, Parker said he only asked for a "precedent for the new signs". In regards to the exact geometry of a football, Parker said he is "not asking for angles and measurements on the sign, just for it to look more like a football". Together with another YouTube mathematics popularizer, Vi Hart, Parker won the 2018 Communications Award of the Joint Policy Board for Mathematics for "communicating the excitement of mathematics to a worldwide audience through YouTube videos, TV and radio appearances, book and newspaper writings, and stand-up comedy". Parker introduced the recreational mathematics concept of a grafting number, an integer with the property that the square root of the integer, when expressed in base "b," will contain the original integer itself before or directly after the decimal point .