Problem of making Silly mistakes in maths exams?

My daughter is studying in 5th standard and she is quite a bright student. She gets 1st rank in her cl always. She even has got many prizes in science and mathematics Olympiads. She is quite bright in maths also. She solves some mathematical problems which may seem complicated even for a 7th grader also. However she has a problem of making silly mistakes in maths. In a maths exam she would have solved a very complicated problem with ease but she would have done a very silly mistake in a relatively simple problem in the same question paper.For example, she would have done addition instead of multiplication. she does these kind of oversight mistakes quite often. Due to these oversights, though she is brilliant in maths, sometimes she gets low scores. Can anyone please suggest me what could be the solution for this problem