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My answer is 272727.
This is how I worked it out. If you take the first example and set
it out like this: (9+) 12 = 21 I worked out that 21 - 12 = 9 and
the same with 51 - 15 = 36 (second example).
Therefore 414141 - 141414 has to equal the secret number, which is
272727.
Solution 2
From Hang Hao who goes to Pei Hwa
Presbyterian Primary School, Singapore:
The answer to this problem is 272727.
Reversing 141414 gives 414141.
The secret number add 141414 gives 414141.
Therefore the secret number is obtained by 414141-141414 =
272727.
These two group activities use mathematical reasoning - one is numerical, one geometric.
An investigation involving adding and subtracting sets of consecutive numbers. Lots to find out, lots to explore.
EWWNP means Exploring Wild and Wonderful Number Patterns Created by Yourself! Investigate what happens if we create number patterns using some simple rules.