Stage: 4 Challenge Level: 
The four digits 5, 6, 7 and 8 are put at random in the spaces of the number below:
3 _ 1 _ 4 _ 0 _ 9 2
- Estimate the probability that the answer will be a multiple of 396.
- Calculate the probability and explain your answer.
Short problems. Modulus arithmetic. Probability. Rigid Bodies. Divisibility. Factors and multiples. Forces. physics. engineering. Permutations.
Published November 1996.
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