[VA] Short & Sweet Math Challenge #24: "2019 Spring Special 5-tier"

[Albert Chan]

Homage number 99999 divisibility trick can be used for other numbers.
Example, to do *both* mod 7 and mod 13 at the same time, for X = 20 190 328

7 * 13 = 91
100 (mod 91) ≡ 9
1000 (mod 91) ≡ 90 ≡ -1

X (mod 91) ≡ 20 - 190 + 328 ≡ 158 ≡ 9 + 58 ≡ 67

X (mod 7) ≡ 67 - 63 ≡ 4
X (mod 13) ≡ 67 - 65 ≡ 2