Make a conjecture (and ‘prove’ it) regarding the multiples of 5 having the units digit be five or zero. (

Question

Make a conjecture (and ‘prove’ it) regarding the multiples of 5 having the units digit be five or zero. (

Answer 1

Do you understand the question?  That's the first order of business.

 

If so, why not list the earliest multiples of five, and study them: 5(1), 5(2), 5(3), 5(4), etc.

Work out the above answers and list them. After 6 or more instances, the pattern (suggested in the "make a conjecture" sentence) should become evident.

 

Finally, make some analysis to 'prove' it.