#41 Cryptogram

Cryptograms are encoded sentences where each letter has been substituted for another. A letter may not stand for itself. Can you decode this cryptogram?


#40 Bomber Pilot

Suppose that you are a bomber pilot flying a B-17 during World War II. You know that 4% of bombers get shot down on average on each mission. Calculate the chance that you would successfully fly all the missions of your tour of duty, let’s say 50 (a larger number than was actually asked of air crews), without getting shot down.


#39 Double Twelve Dominoes

Some double twelve dominoes are shown in the phot below. How many dominoes are there in a full double twelve set? How many dots do they have in total?


Photo from another sergio on flickr.

#38 Shade Six

Shade 6 circles on the diagram below, so that each row, column and diagonal has an even number of blank circles.


#37 Maths Textbook

Rachel accidentally tore some consecutive pages out of her Maths textbook. Rachel discovered that the sum of the page numbers was 261.


How many pages and what were the page numbers on the pages Rachel tore out of her book?

#36 Five Cards

Zoe had these five numbered cards:


How many five-digit numbers can she make that are divisible by 9 without having a remainder?

#35 Counters



A total of 16 counters are put into four piles so that each pile has a different number of counters. List all possible arrangements of the counters. Write, and solve, a further question for investigation similar to this.