2. The expression $2-0-1-9$ contains four digits and three minus signs. What is the largest value that can be obtained by inserting exactly one pair of brackets into the expression?
A 13
B 12
C 10
D 9
E 8
2. B Since $2+0+1+9=12$ and by inserting brackets only + or - signs are possible between the numbers, no value greater than 12 may be obtained. Also, $2-(0-1-9)=2-0+1+9=12$ and hence a result of 12 is possible. Therefore the largest possible value that can be obtained is 12 .