What is the next number in the series: 64, 52, 29, 85, 89?

Answer 1

64, 52, 29, 85, 89, 145

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The next number is the sum of the square of the digits of the previous number:
64 --> 6^2+4^2=36+16=52
52 --> 5^2+2^2=25+4=29
29 --> 2^2+9^2=4+81=85
85 --> 8^2+5^2=64+25=89
89 --> 8^2+9^2=64+81=145