They had then tried the back gate and failed.
Burning tar and oil had stopped them at Constantinople.
Charles the Hammer had stopped them at Tours.
So Europe was saved from the Moslems and from the Moslem religion of Islam. Yet we may wonder what Europe would have been like if the Moslem Arabs had conquered, for the Arabs were in many ways a great people, and we have learned many things from them. Here are some of the things.
The Phenicians invented our alphabet, but the Arabs invented the figures which we use to-day in arithmetic. 1, 2, 3, 4, and so on are called Arabic figures. The Romans used letters instead of figures, V stood for 5, X for 10, C for 100, M for 1000, and so on. Think how difficult it must have been for a Roman boy to add such numbers as
| IV | |
| XII | |
| + | MC |
| CXII | |
| VII | |
| —— |
They could not be added up in columns as we do. And when you think of multiplying and dividing with Roman numbers, it seems almost impossible, for example:
MCMCXVII
× XIX
Occasionally you may see Roman figures still used—on clock-faces, for instance—but all the figures that you use every day in your arithmetic and that your father uses at the bank or store or office are Arabic figures.
Another thing: