#4 Addition subtraction
Set by Katie Steckles
It is true that 1 + 2 + 3 = 3 + 2 + 1, and the equation remains true if you remove two of the plus symbols: 1 + 23 = 3 + 21.
Starting from the equation 1 + 2 + 3 + 4 = 4 + 3 + 2 + 1, delete three of the plus symbols so the equation is still true.
Can you find a way to do the same for 1 + 2 + 3 + 4 + 5 = 5 + 4 + 3 + 2 + 1, but this time by removing a different set of three pluses than you did in the previous case?
Solution next week
#3 Page turner
A book with 24 pages would need nine one-digit page numbers and 15 two-digit page numbers, making a total of 39 digits.
Generally, it is nine digits for pages 0-9, another 180 digits for pages 10-99 and then three digits per number above that (until you get to page 1000, which most books don鈥檛!).
With 183 digits, there would be 96 pages (183 鈥� 9 leaves 174 digits from two-digit page numbers and 174/2 + 9 = 96).
A book that uses 636 digits for its page numbers would have 248 pages.
Quick quiz #236
set by Bethan Ackerley
1 What is it called when certain plants of the same species in a given area synchronise and produce an abundance of seeds periodically?
2 Bosons with a spin value of 0 are known as what?
3 The branch of finite geometry concerned with algebraic and analytic geometry over a finite field is named after which French mathematician?
4 Rickets is caused by a deficiency of which vitamin?
5 The feather-like gill that many molluscs use to respire is known as what?
Quick quiz #236
1 Masting
2 Scalar bosons
3 茅variste Galois
4 Vitamin D
5 The ctenidium