petroglyphs
10000
There are 2704 of them between 1000 and 10000 inclusive.
there are 10 palindromic numbers between 9000 and 10000 9009,9119,9229,9339,9449,9559,9669,9779,9889,9999
There is an infinity of numbers between 8500 and 10000. For example 8605+sqrt(2).
the trick to this is to realize the pattern: 10000=0+10000 10000=1+9999 10000=2+9998 ... 10000=4999+5001 so there are 5000 (10000s) and the unmatched 5000 in the middle = 50,005,000
40
10000
Int(10000/3) = Int(3333.3) = 3333
1-10000 Simple, minus 10,000 by 2 There's your answer. 99,998
9990
It is: 15,000
9950