313+88 = 313 + (87+1) = (313 + 87) + 1 = 400+1 = 401
94+628 = 628 + 94 = 628 + (72+22) = (628 + 72) + 22 = 700 +22 = 722
166 + 255 = 100 + 66 + 200 +55 = (100 +200) + 66 + (34+21) = 300 + (66 + 34) + 21= 300 + 100 +21 = 400+21=421
2088+233=2000+88+200+33=(2000+200)+88+(12+21)=2200+(88+12)+21=2200+100+21=2300+21=2321