1+4=5
( ) 看他們之間的比值,也就是2是1的兩倍,5是4的1.25倍,最後乘上答案的5
2+5=12........5*(2/1)*(5/4)=12.5....無條件捨去法後為12
3+6=21........12*(3/2)*(6/5)=21.6...無條件捨去法後為21
4+7=32........21*(4/3)*(7/6)=32.67..無條件捨去法後為32
5+8=45........32*(5/4)*(8/7)=45.71..無條件捨去法後為45
6+9=60........45*(6/5)*(9/8)=60.75..無條件捨去法後為60
7+10=77.......60*(7/6)*(10/9)=77.78.無條件捨去法後為77
8+11=96.......77*(8/7)*(11/10)=96.8.無條件捨去法後為96