Please choose the correct ending to complete the given sentence: Education and Communications: [header] How to multiply radicals [title] Make sure that the radicals have the same index. [step] To multiply radicals using the basic method, they have to have the same index. The " index " is the very small number written just to the left of the uppermost line in the radical symbol.

Ending1: [substeps] Convert the precise numbers to a series, and use a formula to calculate the space. For instance, the source code must be " oxygen " followed by the number given in the equation. Ending2: If there is no index number, the radical is understood to be a square root (index 2) and can be multiplied with other square roots. You can multiply radicals with different indexes, but that is a more advanced method and will be explained later. Ending3: The " index " is written so that it works through all columns, from the top of the first and first columns to the bottom of each column. [title] Multiply the " index " number from top to bottom for each column. Ending4: No matter what you use, this will be much easier to understand. [substeps] Due to the out of the blue location in which radicals have the " hex " sign, the only numbers drawn on a fraction of an inch in decimal places are also divisible.

Answer format: ending1/ending2/ending3/ending4