27
——
3159—3 + 1 + 5 + 9 = 18—1 + 8 = 9
“There is another thing about the figure 9 very curious,” said Marcus. “If you take any number composed of two figures, reverse it, and subtract the smaller from the larger, the sum of the figures in the answer will always be 9.”
This was found to be true, as in the following examples:
96
69
—
27—2 + 7 = 9
54