To add an equation to a document just tap at the top right of a document and select Equation. Letters are printed in italics with more space left in-between spaces are ignored. The codes can also be used in some types of mathematical symbols in the integral included in the example the _ is used to set the lower bound and the for the upper bound.
In an integral math equation in LaTeX the lower limit is taken as a subscript and the upper limit is taken as a superscript.
Y y_0 v_0t frac12at2 y y_0 v_0t frac12at2 Subscripts are written with the _ symbol. X2 sym x__b_1_a__1 x2. Open an example in Overleaf. In such instances superscript is what comes in handy.