If you don't know how much money is loaded onto that gift card, you can always redeem it and check. This is how to check your gift card balance.
How to safely check your balance on a gift card
Online & Mobile Banking
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Gift Card Balance – Apps on Google Play
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How to use a Vanilla Gift Card on - Android Authority
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I googled target gift card balance to check gift card balances. An
How to check your gift card balance
3 Ways to Check the Balance on a Gift Card - wikiHow
How to check your gift card balance
Gift Card Balance - Apps on Google Play
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