Find the smallest positive multiple of 21 that has no digit smaller than 5.

Guest Apr 30, 2021

#1**+2 **

I don't know if there is some kind of algebraic way to find this (I'm pretty sure there isn't) so let's just list the multiples of 21.

**Green = Possible answer**

**Red = Not possible answer**

21, 42, 63, 84, 105, 126, 147, 168, 189, 210, 231, 252, 273, 294, 315, 336, 357, 378, 399, 420, 441, 462, 483, 504, 525, 546, 567, 588, 609, 630, 651, 672, 693, 714, 735, 756, 777, 798, 819, 840, 861, 882, 903, 924, 945, 966, 987, 1008, 1029

**In total, we have 7 positive multiples of 21 that have no digits smaller than 5. Now, we need to figure out the smallest one, which is easy:**

The first green number is **567**, which will therefore be our answer.

**Ans = 567**

Hope this helps :)

NotGuest Apr 30, 2021