Going from Belarusian to Quechua (Runa Simi) has a composite linguistic distance of 86% (heuristic estimate). Below is the dimension-by-dimension breakdown.
Shared vocabulary, cognates, and loanwords.
Morphology, syntax, word order, cases.
Shared sounds and phoneme inventory.
Cyrillic → Latin
Indo-European ↔ Quechuan
The 5 languages with the lowest linguistic distance from Belarusian:
A quick 3-question check between Belarusian and Quechua. No signup.