5+5=10是“十以内的加法”吗? 这个问题并不难于回答。因为10不是“十以内的数”。如果用a表示“十以内的数”,那么a应满足不等式0≤a≤10,而不是满足不等式0≤a≤10,即a属半开区间(0,10)。由于10不属于“十以内的数”,5+5=10当然就不是“十以内的加法”把和为10的加法与纯“十以内的加法”放在一起,正确的说法应该叫“10或10以内 5 + 5 = 10 is “within ten plus”? This question is not difficult to answer. Because 10 is not a “number within ten.” If a is used to mean “within ten”, then a should satisfy the inequality 0≤a≤10 instead of satisfying the inequality 0≤a≤10, that is, a is a semi-open interval (0,10). Since 10 is not a “number within ten”, 5 + 5 = 10, of course, is not “plus within ten” and the sum of 10 and pure “within ten plus” put together, the correct view should be called "10 Or less than 10