I got first
another MW for decaborane, and second
really another left over.
You may try the Diagram with your corrected data and you will easily get the correct answer:
Therein is also an Example Diagram: How to do a "Stoichiometry Problem".
Formulas, in its best sense, ARE ONLY Recipes for “A Picture”, —
If you DON’T catch “The Picture”, you are lost, - for ever! (A++)
There is ONLY one correct Formula for the “Hydrogen”: —
The Atom/Molecule, ITSSELF! (Dr. R. Mory 1968)
"Make it AS SIMPLE AS possible, — BUT NEVER SIMPLER!" (A. Einstein)