To use a blackjack strategy chart for multi-deck games, you should ensure you're using a chart specifically designed for multiple decks, as the odds and optimal plays can differ slightly from single-deck games. The basic structure of the chart remains the same, showing the best actions (hit, stand, double, split) based on your hand and the dealer's upcard. However, multi-deck games may require slight adjustments due to the increased number of cards in play, which can affect bust probabilities and other factors. It's also important to account for any specific house rules, such as whether the dealer stands or hits on soft 17, as these can alter optimal strategy. Overall, the key is to follow the chart’s recommendations for each situation, taking into account the specific multi-deck conditions.