Page 48 - Fixtures
P. 48
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A∪B = A + B − A∩B
10 ×10 ×10 d1d2d3 = d4d5d6 10
. B = 104 . A = 104 d7
A ∩ B = 10
.d1 = d2 = = d7
. A ∪ B = 104 + 104 − 10 = 19990
x [AIME 1993] ( )
4000 ≤ x < 7000
A=5 A=4 ABCD
D = 6 D = 2 D = 0 )D .A = 6
.C 7 B
4 A=4
.1× 5 × 8 × 7
.1× 4 × 8 × 7 8 (D = 8
.1× 4 × 8 × 7
A=5
A=6
.1× 4 × 8 × 7 + 1× 5 × 8 × 7 + 1× 4 × 8 × 7 = 728