There is a number 61 on a whiteboard. Every minute a number is erased and another number is written instead: a product (multiplication) of digits of an old number plus 13. What number will be written on a whiteboard in one hour? (the answer is a number) For example, after the first minute on a whiteboard will be a number 19 = 1 * 6 + 13.

There is a number 61 on a whiteboard. Every minute a number is erased and another number is written instead: a product (multiplication) of digits of an old number plus 13. What number will be written on a whiteboard in one hour? (the answer is a number) For example, after the first minute on a whiteboard will be a number 19 = 1 * 6 + 13.