Divisibility of numbers [Mathematica]

Questions
1

I need to find 2-digit numbers that are divisible by the sum of their digits. I think about ‘select’ and ‘mod’, but I don’t know how do this.

2

Hi Artur,

something like this?

Select[ Range[10, 99], Divisible[#, Total[IntegerDigits[#]]] &]

which gives:

{10, 12, 18, 20, 21, 24, 27, 30, 36, 40, 42, 45, 48, 50, 54, 60, 63,
70, 72, 80, 81, 84, 90}

Cheers,

Marco

3

this is it! Thanks

4

Marco’s way is better, but:

10a+b/.Solve[(10a+b)/k==a+b&&1<=a<=9&&0<=b<=9,{a,b,k},Integers]         

Out[3]= {10, 12, 18, 20, 21, 24, 27, 30, 36, 40, 42, 45, 48, 50, 54, 60, 63, 70, 72, 80, 81, 84, 90}