All you have to do is align the numbers.

And then multiply.

Finally, don't forget the decimal point.

7.54? ×? 45=? 339.3

3.2 1? ×? 9.8=? 3 1.458

3.9? ×? 4.6=? 17.94

1.45? ×? 0.02=? 0.029

Vertical as shown in the figure: