Hi there,

How does your calculation work?

I see your result:
Iteration Frequency
0 1
1 356
2 519
3 2124
4 1124
5 1379
6 1508
7 1980

But, my test gives:
[0] => 1
[1] => 356
[2] => 519
[3] => 2124
[4] => 1124
[5] => 1311
[6] => 1508
[7] => 1980
[10] => 68

See the difference on the 5th iteration. When I look back, this resulted from the following digits:
1000,1011,1101,1110,1112,1121,1211,1222,2111,2122,2212,2221,2223,2232
,2322,2333,3222,3233,3323,3332,3334,3343,3433,3444,4333,4344,4434,4443
,4445,4454,4544,4555,5444,5455,5545,5554,5556,5565,5655,5666,6555,6566
,6656,6665,6667,6676,6766,6777,7666,7677,7767,7776,7778,7787,7877,7888
,8777,8788,8878,8887,8889,8898,8988,8999,9888,9899,9989,9998

A random test with 3433 gives:
#1: 4333 - 3334 = 999
#2: 999 - 999 = 0
#3: 0 - 0 = 0
#4: 0 - 0 = 0
#5: 0 - 0 = 0
#6: 0 - 0 = 0
#7: 0 - 0 = 0
#8: 0 - 0 = 0
#9: 0 - 0 = 0
#10: 0 - 0 = 0

Can you clarify this? Maybe my calculations are wrong.
Thank you.
@ariefbayu