解:13+9等于( 22 ) ∵已知需求出13+9等于多少 X + Y = Z ∴13 + 9 = (10 + 3)+ (10 - 1) = 10 + 3 + 10 - 1 = (10 + 10)+(3 - 1) = 20 + 2 = 22 答:13+9等于22
13分成1+1213+9=1+9+12=10+12=22