Utilize your financial knowledge, give your answer or opinion to the input question or subject . Answer format is not limited.

using credit card and paying back quickly
Yes, however you would have to wait for the $900 to actually be available in your credit card account if making the transaction from an account from another bank or provider, as it usually might take one to two business days for this to happen.  If both the chequing account and credit card account are with the same bank, then usually this will go through straight away, and you will be able to make your next purchase on the same day, but I would check your credit card balance first before making that purchase.