Write an integer that is greater than 100 and can be divided by 3, and find the cubic sum of the numbers on each digit of the number. Repeat the above operation for the sum. What rule do you find when you continue? Then take any integer that meets the conditions and try to verify whether the result is correct I know the answer is 153, but I don't know how to calculate it List a number 123. How can I get 153? Forgive my ignorance If 123 is not OK, what number is OK?

Write an integer that is greater than 100 and can be divided by 3, and find the cubic sum of the numbers on each digit of the number. Repeat the above operation for the sum. What rule do you find when you continue? Then take any integer that meets the conditions and try to verify whether the result is correct I know the answer is 153, but I don't know how to calculate it List a number 123. How can I get 153? Forgive my ignorance If 123 is not OK, what number is OK?

There are many such numbers, such as 3714071634, which are called Narcissus numbers
According to the rules in the title, there is always a number like this, but it is not necessarily 153,
For example, 23 → 35 → 152 → 134 → 92 → 737 → 713 → 371 → 371
When 345 → 216 → 225 → 141 → 66 → 432 → 99 → 1458 → 702 → 351 → 153

A fraction multiplied by an integer 9 times 3 / 19 is equal to?

Denominator unchanged, numerator multiplied by 9

It's eight out of twenty fractions multiplied by integers,

1*8/21=8/21
2*4/21=8/21
4*2/21=8/21
8*1/21=8/21
16*1/42=8/21
32*1/84=8/21