you want to multiply these together
![5.12*4.001=20.48512](https://img.qammunity.org/2019/formulas/mathematics/middle-school/fvn4z2fsqfb5j4yaglx6svp774y2ew37c5.png)
if you did not get this answer you must remember to move the decimal point to the left, the amount of times there are numbers to the right of the decimal point.
.5*1.11=0.555
the 5 is three spaces to the left because there are 3 numbers to the right of the decimal point.
Hope I Helped!