Borrowing ten is a calculation method, that is, if the unit is not reduced enough, subtract the subtraction with 10, add the remainder with the number in the unit, and divide 15 by 10 and 5. Subtracting 9 from 10 is equal to 1, and then adding it with 1.

Extended data:

Learning mathematics is to teach children a series of knowledge such as understanding numbers, four operations, formulas for calculating figures and lengths, and unit conversion through textbooks, so as to lay a good mathematical foundation for junior high school calculation and daily life. Frieden Noel, a Dutch educator, said: "Mathematics comes from reality and must be rooted in reality and applied to reality." Indeed, modern mathematics requires us to observe the world from a mathematical perspective and explain the world in mathematical language. Judging from the mathematics learning psychology of primary school students, the learning process of students is not a passive absorption process, but a reconstruction process based on existing knowledge and experience. Therefore, learning while doing and learning while playing will make children learn more actively. From our educational goal, while imparting knowledge, we should pay more attention to cultivating students' comprehensive ability of observation, analysis and application.