Rectangle cannot be done

When I want to make a rectangle I can´t put the size, it doesn´t recognize or the ENTER botton doesn´t work. please help me

Are you clicking in the Measurements window before typing in the dimensions? If so, don’t! There is never any need to click in the Measurements window before entering the dimension.

Are you typing in the dimensions with the correct separator? Either a comma or semicolon. Look at the measurements box before typing and make sure you use the same separator as shown.

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This tutorial is not perfect and a bit old but it easily explains how to draw a rectangle with precise measurements. Be sure to look at the separators used by sketchup for the measurements as they may be different from the ones I use in the video.