Banded lookup with approximate match
Commission tiers, tax brackets, postage bands and grade boundaries all have the same shape: a list of thresholds, and a rule that a value belongs to the highest threshold it has reached.
That is what approximate match does. With TRUE as the fourth argument, VLOOKUP finds the largest value in the first column that is not greater than what you are looking for. A sales figure of 6,400 finds the 5,000 row.
It only works if the thresholds are sorted smallest first, and if the lowest band starts at zero so that every possible value has somewhere to land. Unsorted thresholds give wrong answers with no error at all.
In C2, find each score's grade from the band table in E2:F6, and fill down to C6.
The grid for this exercise is part of the paid half.
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