There are a lot of Singapore Math & Singapore Math-style curricula nowadays.
I am happiest with Singapore Math "Primary Mathematics US Edition", which is the ur-curriculum and the most Singaporey of them all. Cheap, lots of resources available, plenty of used copies floating around, and as a bonus, your child will be adding and subtracting durian fruit.
Beast Academy is a choice for a child who is very, very good at math; generally speaking, your 95+ percentile kid is the target of that curriculum.