How many moles are present in $2.1 * 10^24$ atoms of calcium?

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Answer 1 · 2016-01-21T07:43:46

There are $6.022140857(74)xx10^(23)$ $"calcium"$ $"atoms"$ in 1 mole of $Ca$ .

You have specified $2.1xx10^24$ calcium atoms.

So $(2.1xx10^24*"calcium atoms")/(6.022xx10^(23)*"calcium atoms mol"^-1)$ $=$ $??$ $mol$

How many moles are present in 2.1 * 10^242.1 * 10^24 atoms of calcium?