# Monthly Archives: September 2019

## DAY/DYDD 273:

The Main Challenge Starting with the number 70, keep on subtracting consecutive prime numbers from the previous total (2, 3, 5, …) until your answer first becomes negative. What is this negative number? The 7puzzle Challenge The playing board of the 7puzzle … Continue reading

## DAY/DYDD 272:

The Main Challenge This 10-step number trail, involving the four arithmetical operations, may leave you in sixes and sevens! Start with the number 6, then: add 7 –6 multiply by 6 +7 divide by 7 subtract 6 +6 ÷7 add 6 … Continue reading

## DAY/DYDD 271:

The Main Challenge If you write out all numbers from 1-100, what is the longest run of consecutive numbers that are NOT prime numbers?  What are the lowest and highest numbers in that run? The 7puzzle Challenge The playing board of the … Continue reading

## DAY/DYDD 270:

The Main Challenge Here’s a crafty Mathelona-style challenge where your task is to make all three lines work out arithmetically by placing digits from 0 to 5 into the 12 gaps, with each digit being inserted exactly TWICE: ◯  +  ◯   = … Continue reading

## DAY/DYDD 269:

The Main Challenge There is just one set of three consecutive numbers in ascending order whose sum is less than 50 and follow this sequence:  square number – triangular number – prime number Can you list this set of three … Continue reading

## DAY/DYDD 268:

The Main Challenge Find the sum of the SEVEN different numbers in the range 65 to 85 that are either multiples of 9, 10, 11 or 12. The 7puzzle Challenge The playing board of the 7puzzle game is a 7-by-7 grid of 49 different … Continue reading

## DAY/DYDD 267:

The Main Challenge Using all four numbers 1, 5, 5 and 10 once each, with + – × ÷ available in each calculation, which even number from 2 to 20 inclusive is impossible to make? The 7puzzle Challenge The playing board of the 7puzzle game is a 7-by-7 … Continue reading

## DAY/DYDD 266:

The Main Challenge Using all four numbers 2, 4, 7 and 8 once each, with + – × ÷ available, show how you can make the following six target numbers: 8     18     28     38     48     58 The 7puzzle Challenge The … Continue reading