The math is wrong. Trump won 89 delegates, giving him 845 delegates. Needed to win 1237: 1237 - 845 = 392 delegates. There are 734 remaining delegates. 392/734 = 53.4%. 56% of the remaining 734 delegates will 411 delegates or a total of 1256 delegates. That’s 19 delegates more than is necessary to win nomination.
Green Papers states that there are 620 delegates remaining.