Răspuns:
76
Explicație pas cu pas:
21 : 21 = 1 rest 0
21 : 20 = 1 rest 1
21 : 19 = 1 rest 2
21 : 18 = 1 rest 3
21 : 17 = 1 rest 4
21 : 16 = 1 rest 5
21 : 15 = 1 rest 6
21 : 14 = 1 rest 7
21 : 13 = 1 rest 8
21 : 12 = 1 rest 9
21 : 11 = 1 rest 10
21 : 10 = 2 rest 1
21 : 9 = 2 rest 3
21 : 8 = 2 rest 5
21 : 7 = 3 rest 0
21 : 6 = 3 rest 3
21 : 5 = 4 rest 1
21 : 4 = 5 rest 1
21 : 3 = 7 rest 0
21 : 2 = 10 rest 1
21 : 1 = 21 rest 0
................................
21 : 22 = 0 rest 21
21 : orice alt numar > 21 = 0 rest 21
Suma resturilor posibile = 0+1+2+3+4+5+6+7+8+9+10+21 =
= (1+10)·10:2 + 21 = 11·5 + 21 = 55+21 = 76
