how this base works: it is similar to factorial base but it is a double factorial instead. so like 1x3x5 or 2x4x6. in this case it starts with odds so ones place = 1!! = 1 = 1 and tens place = 3!! = 3x1 = 3 and hundreds = 5!! = 5x3x1 = 15, and thousands = 7!! = 7x5x3x1 = 105, and so on.
