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Warnings do not stop the execution of a function. The warning messages can clutter the results. It is best to correct the cause of the warnings. In this instance, set two vectors a and b of the same length and complete the multiplication again.

R console and R Notebooks  ("Advanced" users)

The R console can be opened from (1) the command-prompt in Windows or in the terminal in MacOs and Unix. By typing the command R, a R console opens automatically. This command is part of the R installation (see What is R programming language?.) Advanced users who are familiarised with such tools should explore this option. 

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