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Problems


IDDescription / TitleSolved By
151Paper sheets of standard sizes: an expected-value problem
2873
152Writing 1/2 as a sum of inverse squares
1376
153Investigating Gaussian Integers
1345
154Exploring Pascal's pyramid
1415
155Counting Capacitor Circuits
1866
156Counting Digits
1278
157Solving the diophantine equation 1/a+1/b= p/10n
1433
158Exploring strings for which only one character comes lexicographically after its neighbour to the left
1998
159Digital root sums of factorisations
1815
160Factorial trailing digits
1779
161Triominoes
1121
162Hexadecimal numbers
3106
163Cross-hatched triangles
1025
164Numbers for which no three consecutive digits have a sum greater than a given value
3259
165Intersections
1406
166Criss Cross
2235
167Investigating Ulam sequences
948
168Number Rotations
1492
169Exploring the number of different ways a number can be expressed as a sum of powers of 2
2647
170Find the largest 0 to 9 pandigital that can be formed by concatenating products
1083
171Finding numbers for which the sum of the squares of the digits is a square
1469
172Investigating numbers with few repeated digits
2113
173Using up to one million tiles how many different "hollow" square laminae can be formed?
5234
174Counting the number of "hollow" square laminae that can form one, two, three, ... distinct arrangements
3454
175Fractions involving the number of different ways a number can be expressed as a sum of powers of 2
1041
176Right-angled triangles that share a cathetus
1099
177Integer angled Quadrilaterals
737
178Step Numbers
1932
179Consecutive positive divisors
6503
180Rational zeros of a function of three variables
882
181Investigating in how many ways objects of two different colours can be grouped
1088
182RSA encryption
1450
183Maximum product of parts
2821
184Triangles containing the origin
920
185Number Mind
1760
186Connectedness of a network
1604
187Semiprimes
6357
188The hyperexponentiation of a number
3828
189Tri-colouring a triangular grid
1126
190Maximising a weighted product
2386
191Prize Strings
4081
192Best Approximations
890
193Squarefree Numbers
1775
194Coloured Configurations
799
195Inscribed circles of triangles with one angle of 60 degrees
747
196Prime triplets
1369
197Investigating the behaviour of a recursively defined sequence
3030
198Ambiguous Numbers
632
199Iterative Circle Packing
1031
200Find the 200th prime-proof sqube containing the contiguous sub-string "200"
1282