Non-repeating 30101

1. How many different options are there for exchanging a ten-euro bill with one-euro, two-euro, and five-euro bills?
a) 5 b) 8 c) 14 d) 10

2. How many non-repeating three-digit numbers can be written using odd digits?
a) 999 b) 225 c) 60 d) 25

Correct answer:

n1 =  10
n2 =  60

Step-by-step explanation:

10 = 1a+2b+5c a1=0, b1=0, c1=2 a2=0, b2=5, c2=0 a3=1, b3=2, c3=1 a4=2, b4=4, c4=0 a5=3, b5=1, c5=1 a6=4, b6=3, c6=0 a7=5, b7=0, c7=1 a8=6, b8=2, c8=0 a9=8, b9=1, c9=0 a10=10, b10=0, c10=0 n1=10
1,3,5,7,9 n2=5 4 3=60

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