# Wrong, But Useful: Episode 39

/podcasts/wbu39.mp3

In this month’s Christmassy episode of Wrong, But Useful, @reflectivemaths and I discuss:

- Number of the podcast: 9
- Shout outs to:
- @aap03102 (Chris Smith) for his maths newsletter
- @mathistopheles (Thomas Oléron Evans) and @fryrsquared (Hannah Fry) for sending me a copy of their book
- @chalkdustmag for the lovely card

- @fryrsquared - The Joy of Data on BBC four
- Mathematics exhibition at the Science Museum
- “Did you know that the incircle of a 3-4-5 triangle has radius 1?”
- (Via @arithmaticks): owt to the nowt = 1
- Class “Girls were better than boys by 1”
- (Via @danicquinn): How would you do 12.5 x 140 ?
- (Via @christianp): suppose you want students to round -2.3. You round it to the nearest…?
- New GCSE mocks
- @jamesgrimes’s personalised video for Dave and his classes and his MathsJam talk
- Puzzles:
- From Ep 37: 2, 3 and 7 are the three numbers whose reciprocals don’t reach 1, but get as close as possible. Gold stars to @fenneklyra, @chrishazell72, @dragon_dodo, and @aap03102
- From Ep 38: Another gold star to @FennekLyra for solving the 100! Puzzle, which we won’t give away the answer to.
- How many gifts are there, in total, in the Twelve Days of Christmas? And what do you end up with most of? What if there were 24 days of Christmas?