73-2×5=63, divisible by 7.
735 is divisible by 7.
(2) Whether 588-2× 0 is divisible by 7 and whether 5880 is divisible by 7;
588-2×0=588, divisible by 7.
5880 is divisible by 7.
(3) Write another number with the above properties;
4935
493-5×2=483, divisible by 7.
Then 4395 can be divisible by 7.
(4) Observing the above figures, can you sum up any rules?
A number, a new number obtained by subtracting a number and twice the original number.
If the difference is divisible by 7, then this number can be divisible by 7.