Răspuns:
a) din teorema imprtirii cu rest => R < I
I=11 => R=0,1,2...10
R=C unde C≠0
a:11=1 rest 1=>a=11·1+1=>a=12
a:11=2 rest 2=>a=11·2+2=>a=24
.
a:11=10 rest 10=>a=11·10+10=>a=120
nr sunt : 12 , 24, 36 , 48 , 60 , 72 , 84 , 96 , 108 , 120
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I=13=>R=0,1,2...12
R=2C=>C=R/2=>C=1 , 2 , 3 , 4 , 5 , 6
a:13=1 rest 2=>a=13·1+2=>a=15
a:13=2 rest 4=>a=13·2+4=>a=30
.
a:13=6 rest 12=>a=13·6+12=>a=90
nr sunt: 15 , 30 , 45 , 60 , 75 , 90
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I=9 => R=0,1,2...8
a:9=4 rest 0=>a=9·4+0=>a=36
a:9=4 rest 1=>a=9·4+1=>a=37
.
a:9=4 rest 8=>a=9·4+8=>a=44
S=36+37+38+39+40+41+42+43+44
S=360
