1. Between the numbers $1,2,3,4,5,6,7,8,9$ insert arithmetic operation signs and parentheses so that the resulting expression has a value of 100.
1. a) $1+2+3+4+5+6+7+8 \times 9=100$;

b) $1 \times 2 \times 3+4+5+6+7+8 \times 9=100$;
c) $1+2 \times 3+4 \times 5-6+7+8 \times 9=100$;

d) $1 \times 2 \times 3 \times 4+(5+6-7)+8 \times 9=100$

e) $(1 \times 2+3) \times 4 \times 5+6-7-8+9=100$;

f) $(1+2+3) \times(4+5+6)-7+8+9=100$;

g) $((1+2): 3+4+5-6) \times 7+8 \times 9=100$.