50剪43等于7,51减去44等于七,52减去45等于七,53减去46等于7,54减去47等于7,55减去48等于7,56减去49等于7,57减去50等于7,58剪去50等于7,59减去八等于7。
10-3=7
9-2=7
8-1=7