There is the machine A which displays the number of double-digit figures, and when a switch is turned on, a number will be displayed as the following rule for every second.
[Rule]
As for tens digit, it changes every second in order of 1, 2, 3, 4, 5, 6, 7, 8 and after 8 it return to 1 again. It changes in a same cycle.
As for ones digit, it changes every second in order of 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 and after 0 it return to 1 again. It changes in a same cycle.
For example, when a switch is turned on, one second after 11 will be displayed, two seconds after 22 will be displayed, three seconds after 33 will be displayed, nine seconds after 20 will be displayed and eleven seconds after 31 will be displayed.
Answer the following questions.
(1) After turning on a switch, in how many seconds is it that 73 will be displayed for the first time ?
(2) If each number of double-digit figures which can be displayed by this machine A is added altogether, how much is it ?
(3) There is the machine B which displays the number of triple-digit figures according to the rule as machine A.
It displays both tens digit and ones digit as same as the machine A.
As for hundreds digit, it changes every second in order of 7, 6, 5, 4, 3, 2, 1 and after 1 it return to 7 again. It changes in a same cycle.
For example, when a switch is turned on, one second after 711 will be displayed, two seconds after 622 will be displayed and eight seconds after 788 will be displayed.
(a) After turning on a switch, in how many seconds is it that 711 is displayed on the 2nd times?
(b) After turning on a switch, in how many seconds is it that 773 is displayed for the first time?