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Choose four different digits from 1-9 and put one in each box so that the resulting four two-digit numbers add to a total of 100.
Can you arrange the numbers 1 to 17 in a row so that each adjacent pair adds up to a square number?
Can you picture how to order the cards to reproduce Charlie's card trick for yourself?
How many solutions can you find to this sum? Each of the different letters stands for a different number.
The clues for this Sudoku are the product of the numbers in adjacent squares.
Five numbers added together in pairs produce: 0, 2, 4, 4, 6, 8, 9, 11, 13, 15 What are the five numbers?