[Math] 16 digit numbers divisible by 17

Question

I wanted to know about the $16$ digit numbers those are divisible by $17$ and when this $16$ digit number is broken in groups of $4$ those groups of four are also divisible by $17$ and a check to verify their occurrence.

Emma.

Answer 1

Use a divisibility rule:

Subtract 5 times the last digit from the rest, e.g. $221: 22 − 1\times 5 = 17.$