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Problems


IDDescription / TitleSolved By
151Paper sheets of standard sizes: an expected-value problem
2864
152Writing 1/2 as a sum of inverse squares
1372
153Investigating Gaussian Integers
1342
154Exploring Pascal's pyramid
1413
155Counting Capacitor Circuits
1861
156Counting Digits
1274
157Solving the diophantine equation 1/a+1/b= p/10n
1426
158Exploring strings for which only one character comes lexicographically after its neighbour to the left
1991
159Digital root sums of factorisations
1807
160Factorial trailing digits
1773
161Triominoes
1119
162Hexadecimal numbers
3101
163Cross-hatched triangles
1023
164Numbers for which no three consecutive digits have a sum greater than a given value
3251
165Intersections
1402
166Criss Cross
2231
167Investigating Ulam sequences
947
168Number Rotations
1486
169Exploring the number of different ways a number can be expressed as a sum of powers of 2
2636
170Find the largest 0 to 9 pandigital that can be formed by concatenating products
1082
171Finding numbers for which the sum of the squares of the digits is a square
1463
172Investigating numbers with few repeated digits
2109
173Using up to one million tiles how many different "hollow" square laminae can be formed?
5219
174Counting the number of "hollow" square laminae that can form one, two, three, ... distinct arrangements
3448
175Fractions involving the number of different ways a number can be expressed as a sum of powers of 2
1040
176Right-angled triangles that share a cathetus
1097
177Integer angled Quadrilaterals
737
178Step Numbers
1931
179Consecutive positive divisors
6488
180Rational zeros of a function of three variables
882
181Investigating in how many ways objects of two different colours can be grouped
1087
182RSA encryption
1448
183Maximum product of parts
2813
184Triangles containing the origin
915
185Number Mind
1757
186Connectedness of a network
1600
187Semiprimes
6342
188The hyperexponentiation of a number
3818
189Tri-colouring a triangular grid
1124
190Maximising a weighted product
2381
191Prize Strings
4068
192Best Approximations
889
193Squarefree Numbers
1772
194Coloured Configurations
795
195Inscribed circles of triangles with one angle of 60 degrees
744
196Prime triplets
1363
197Investigating the behaviour of a recursively defined sequence
3024
198Ambiguous Numbers
630
199Iterative Circle Packing
1030
200Find the 200th prime-proof sqube containing the contiguous sub-string "200"
1279