Problem / game
First name
Crane Class
School
Larkrise Primary, Oxford
Country
Age
11
Filename
We tested it lots of times and found that the trick works for 2 digit numbers where the digits add up to <10.
Paddy, Dai Dai, Zulekha and Ottilie worked together to work out that you can make it work for numbers where the digits sum >10. When you have a two digit total, use the 'ones' as the middle number and add the tens on to the left hand number. See the attached picture.
William wondered if it worked for three digit numbers... It didn't!
Mustafa wondered if it would work for decimal numbers. It did, as long as you put the decimal point back in to the right of the total in the middle.
Zulekha noticed that you could use the trick to multiply numbers by 11, then double them or quadruple them etc to find x22/33/44/55/66/77/88/99!