Are you smarter than a Singaporean high school student? Here’s one way to find out. 
 
 A math problem intended for sophomores and juniors in Singapore has become the obsession of some portion of the Internet over the past few days. The students were asked to answer a seemingly simple question: “When is Cheryl’s birthday?” 
 
 To figure it out, you’re provided with some vague clues. Cheryl separately gives two new friends some details about when she was born, including a list of 10 possible birth dates. She also tells one of the friends, Albert, the month of her birthday, then tells the other friend, Bernard, the day of her birthday. 
 
 As a final clue, there’s a conversation between Albert and Bernard, in which they each talk about what they know. 
 
 Now go solve the riddle! 
 
 Stumped? You’re not alone. 
 
 The question first appeared on April 8, as part of the Singapore and Asian Schools Math Olympiads contest. It was posted online Friday by a Singaporean television presenter and quickly went viral — perhaps because the problem was initially misidentified as one intended for 10- and 11-year-olds. 
 
 As the problem spread far and wide, it became a bit of a joke. Truthfully, we blame no one for choosing to laugh instead of crying out of frustration. 
 
 Albert and Bernard later went out and over drinks, compared notes and decided Cheryl and her frigging birthday wasn't worth their time. — mrbrown (@mrbrown) April 14, 2015 
 
 So when is Cheryl's birthday? Just check her Facebook. — Songhua (@songboh) April 12, 2015 
 
 There was so much attention focused on this problem that the Singapore and Asian Schools Math Olympiads organizers released a statement clarifying who the problem was intended for, so that “Singapore parents will not start to worry so much.” 
 
 [The inside story of the ‘white dress, blue dress’ drama that divided a planet] 
 
 The question is actually from a test given to students who are sophomores or juniors in high school — not middle school kids. And it comes deep into the exam and is one of the more difficult problems that students encounter. 
 
 “Being Question 24 out of 25 questions, this is a difficult question meant to sift out the better students,” Math Olympiads organizers wrote in a statement. “SASMO contests target the top 40% of the student population and the standards of most questions are just high enough to stretch the students.” 
 
 So yes, breathe a sigh of relief. And then take out a pencil and paper. 
 
 [How a middle school math teacher became Jordan Spieth’s caddie] 
 
 By this point there are more than a few answers out there, including the official one from SASMO. 
 
 And here is a video tutorial that can walk you through the solution: ||||| Image copyright Kenneth Kong Image caption The logic question posted by Mr Kong is now known as 'Cheryl's Birthday' 
 
 A school maths question posted on Facebook by a Singaporean TV presenter has stumped thousands, and left many asking if that's really what is expected of Singaporean students. 
 
 The question asks readers to guess the birthday of a girl called Cheryl using the minimal clues she gives to her friends, Albert and Bernard. 
 
 Cheryl's Birthday was initially reported to be an examination question for 11-year-olds. 
 
 Students stressed by tough examinations is a perennial issue here, and Cheryl's Birthday reignited concerns that the education system was too challenging. 
 
 Image copyright facebook 
 
 But it later emerged it was for students aged about 15 taking part in last week's Singapore and Asian Schools Math Olympiads (Sasmo). 
 
 Organisers said the test was aimed at the top 40% and aimed to "sift out the better students", adding it was "important to clarify so that Singapore parents will not start to worry so much". 
 
 Image copyright Twitter 
 
 Kenneth Kong, who first posted the problem, told the BBC: "It's a really difficult question for younger kids, so that's why people were so shocked at first... but now that people know it's for older students, they just think it's quirky." 
 
 Media playback is unsupported on your device Media caption Author and mathematician Alex Bellos demonstrates how to solve the problem 
 
 Sasmo's executive director Henry Ong defended the question, saying there was "a place for some kind of logical and analytical thinking in the workplace and in our daily lives". 
 
 Image copyright Twitter 
 
 "We are not saying this problem is for every student... But if these kind of problems can be used to stretch the better students to sharpen their analytical power, why not?" 
 
 The question, which has been shared around the world, sparked a Twitter hashtag #cherylsbirthday and even a music track. 
 
 "After spending so much time together, thinking of Cheryl's birthdate, Albert and Bernard soon fell in love with each other and forgot all about Cheryl," said Elfy Bianca Hassan on Mr Kong's page. 
 
 "Dump her. Find other girls," suggested Nicholas Lim. 
 
 Image copyright Twitter 
 
 Others took umbrage at the wording. "I hope people picked up that the person who set the question needs to go for English grammar classes - there are at least two grammar errors," said Clarence Singam-Zhou. 
 
 So when is Cheryl's birthday? 
 
 The answer is 16 July, said Sasmo which posted the correct solution. 
 
 Image copyright Twitter 
 
 Sasmo also dismissed an "alternative solution" which resulted in 17 August. 
 
 Their rejection was that "since Bernard did not say that he does not know when Cheryl's birthday is, then how did Albert know that Bernard does not know?" 
 
 Problem solved. ||||| Hello guzzlers. 
 
 Welcome to the second instalment of my new puzzle series. 
 
 Last time I asked you about Denise and her birthday. Today it’s a totally different style of problem 
 
 In colour! 
 
 Look at the image above. Which is the odd one out and why? 
 
 
 
 You want more? 
 
 Okay, here’s a second puzzle. It’s from the first grade admissions test for the Hong Kong Elementary School. So it’s for six year olds. 
 
 
 
 It went viral a year ago - but many of you will not have seen it. 
 
 Which parking spot number is the car parked on? 
 
 Can you solve it in 20 seconds, as the children were expected to do? 
 
 Twenty seconds is all you get ... 
 
 I’ll be posting the answers on this blog later today. If you’d prefer to watch the video of this problem, here it is: 
 
 Sorry, your browser is unable to play this video. Facebook Twitter Pinterest 
 
 Odd-one-out puzzle devised by Tanya Khovanova. 
 
 
 
 I post a puzzle here on a Monday every two weeks. If you like this sort of thing check out my other Guardian blog Adventures in Numberland. You can also check me out on Twitter, Facebook, Google+ and my personal website. 
 
 If you create puzzles and fancy seeing one published here get in touch.
– Last month the Internet went nuts trying to figure out Cheryl's birthday. Today, Alex Bellos is back in the Guardian with two more stumpers, what he calls the "second installment" in his let's-drive-everyone-mad puzzle series (the first was a sequel to the Cheryl's birthday puzzle). The reason it comes with the title "Are you smarter than a Hong Kong six-year-old?" is that Bellos actually took the first puzzle from an admissions test for first grade in Hong Kong. You only have 20 seconds to solve it, just like the schoolkids did. Got it? We'll direct you to the answer, but not before you head to the Guardian to view the second visual doozy. All you have to do there is figure out which shape is the odd one out. Answers to both here. (Click to read about the Internet's most mysterious puzzle.)