MathDB
2018 PUMaC Live Round 4.3

Source:

January 13, 2019
PuMACLive Round

Problem Statement

Let 0≤a,b,c,d≤100\leq a,b,c,d\leq 10. For how many ordered quadruples (a,b,c,d)(a,b,c,d) is ad−bcad-bc a multiple of 11?11?
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