noun
total bases
Baseball statistic: the sum of bases a batter reaches from hits (single=1, double=2, triple=3, home run=4).
彼はこの試合で塁打数を5に伸ばした。
He increased his total bases to 5 in this game.
長打率 (slugging percentage) is 塁打数 divided by 打数, measuring power hitting.
Compound of 塁打 (base hit, from 塁 'base' and 打 'hit') + 数 (number).