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Weekly Problem 51 - 2006

Stage: 3 and 4 Challenge Level: Challenge Level:1

If the pattern below is continued, what number will appear directly below 400?

      1      
    2 3 4    
  5 6 7 8 9  
10 11 12 13 14 15
16 
 
 
If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.   

This problem is taken from the UKMT Mathematical Challenges.

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