If you need both, and you have both the numerator and denominator in a V memory register, it's best to do it "the old way" because the DIV PLC instruction does both at the same time. The MATH IBoxes have to do funky math accumulator stack manipulation to work properly to do JUST a divide or JUST a mod. You actually would end up doing TWO DIV instructions with the two expressions
MATH divresult "Numerator / Denominator"
MATH modresult "Numerator % Denominator "
You would be best off doing in the native math instructions (no IBox)
LD Numerator
DIV Denominator
OUT divresult
POP
OUT modresult