To ‘fossilise’ a number, you just multiply its digits together. Then do the same with the result, repeating the process until the number remaining has only one digit.
If this digit is zero, we say that the
number leaves no fossil.
288 gives 2 x 8 x 8 = 128
128 gives 1 x 2 x 8 = 16
16 gives 1 x 6 = 6.
say that 489 leaves a fossil of 6.
1. Find a number with 5 digits that leaves a fossil of 6. Too easy?
If all the original digits have to be different, can you find one?2. What is the largest 3-digit number that leaves a fossil of 4?
3. Find the largest number whose digits are all different, that leaves a fossil.
4. Find the largest number, whose digits are all different, that leaves an odd number for a fossil.
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