I don& think i ever knew this. the number below the # being multipled by 9 . like 2 then the second number is whatever is added to get 9 . answer hope that makes sense lol :)

Runde's Room: Math Journal Sundays - Metric Conversions Convert among different-sized standard measurement units within a given measurement system (e., convert 5 cm to m), and use these conversions in solving multi-step, real world problems.