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Problems


IDDescription / TitleSolved By
151Paper sheets of standard sizes: an expected-value problem
2963
152Writing 1/2 as a sum of inverse squares
1423
153Investigating Gaussian Integers
1388
154Exploring Pascal's pyramid
1456
155Counting Capacitor Circuits
1921
156Counting Digits
1301
157Solving the diophantine equation 1/a+1/b= p/10n
1465
158Exploring strings for which only one character comes lexicographically after its neighbour to the left
2051
159Digital root sums of factorisations
1851
160Factorial trailing digits
1824
161Triominoes
1150
162Hexadecimal numbers
3174
163Cross-hatched triangles
1048
164Numbers for which no three consecutive digits have a sum greater than a given value
3347
165Intersections
1440
166Criss Cross
2291
167Investigating Ulam sequences
970
168Number Rotations
1520
169Exploring the number of different ways a number can be expressed as a sum of powers of 2
2734
170Find the largest 0 to 9 pandigital that can be formed by concatenating products
1107
171Finding numbers for which the sum of the squares of the digits is a square
1508
172Investigating numbers with few repeated digits
2170
173Using up to one million tiles how many different "hollow" square laminae can be formed?
5350
174Counting the number of "hollow" square laminae that can form one, two, three, ... distinct arrangements
3525
175Fractions involving the number of different ways a number can be expressed as a sum of powers of 2
1060
176Right-angled triangles that share a cathetus
1121
177Integer angled Quadrilaterals
747
178Step Numbers
1980
179Consecutive positive divisors
6650
180Rational zeros of a function of three variables
897
181Investigating in how many ways objects of two different colours can be grouped
1120
182RSA encryption
1485
183Maximum product of parts
2879
184Triangles containing the origin
941
185Number Mind
1804
186Connectedness of a network
1648
187Semiprimes
6520
188The hyperexponentiation of a number
3904
189Tri-colouring a triangular grid
1150
190Maximising a weighted product
2445
191Prize Strings
4191
192Best Approximations
906
193Squarefree Numbers
1807
194Coloured Configurations
808
195Inscribed circles of triangles with one angle of 60 degrees
763
196Prime triplets
1406
197Investigating the behaviour of a recursively defined sequence
3102
198Ambiguous Numbers
641
199Iterative Circle Packing
1060
200Find the 200th prime-proof sqube containing the contiguous sub-string "200"
1311