2 010 - ( 7 × 8 + a × 4 - 45 : 5 × 8 ) = 2 006
56 + a × 4 - 9 × 8 = 2 010 - 2 006
56 + a × 4 - 72 = 4
56 + a × 4 = 4 + 72
56 + a × 4 = 76
a × 4 = 76 - 56
a × 4 = 20
a = 20 : 4
a = 5 → numarul, aflat prin metoda mersului invers
Verific:
2 010 - ( 56 + 5 × 4 - 72 ) = 2006
= 2010 - ( 76 - 72 ) =
= 2010 - 4 =
= 2006
