Trump has accumulated at least 678 of 1413 delegates awarded so far, 47.98%.
Trump's current total of 678 will rise (to 690?) after Missouri is adjudicated, so he actually needs fewer than 559 delegates (547?).
Missouri expects to award Trump an additional 12 delegates on top of the current 25, as reported here:
On Wednesday, the Missouri Republican Party announced Trump had won 37 delegates, and Cruz won 15.
About only one third of remaining delegates come from states with proportional contests. The rest are in winner take all states.