#1 Digital sevens
Set by Katie Steckles
Welcome to our new puzzle column!
Our devious BrainTwister enigmas will start with a first step, then add a twist (or two) to get you thinking about the problem differently.
61, 14234, 25, 1111111 and 95 are all numbers whose digits add to a multiple of 7.
What is the next number after 95 whose digits add to a multiple of 7?
Can you find a pair of consecutive numbers whose digits both add to multiples of 7?
What about a pair of numbers under 100 whose digits both add to multiples of 7, but that are two apart rather than consecutive?
Solution next week
#255 Final light bulb moment
Solution
The lights will all be on after exactly 255 seconds.
The lights are behaving like 1s and 0s in binary. Starting at 00000000, they pass through each number, 00000001, 00000010, 00000011 and so on until reaching 11111111. This is the binary code for 255.
Quick quiz #233
set by Bethan Ackerley
1 How old was Louis Braille when he invented his eponymous writing system, 200 years ago this year?
2 Which substance is Charles Romley Alder Wright best known for synthesising, 150 years ago this year?
3 What was the name of the first operational nuclear-powered submarine, which entered service 70 years ago this month?
4 The AL 288-1 Australopithecus fossil, better known as "Lucy" or "Dinkinesh", was discovered in which country 50 years ago this year?
5 The Vera C. Rubin Observatory is tasked with carrying out which astronomical survey when it becomes fully operational later this year?
Quick quiz #233
Answers
1 15
2 Heroin (also known as diamorphine or diacetylmorphine)
3 The USS Nautilus
4 Ethiopia
5 The Legacy Survey of Space and Time